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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.100 by root, Fri Oct 2 20:41:56 2009 UTC vs.
Revision 1.143 by root, Fri Mar 23 17:54:36 2012 UTC

…		…
30	rcv $port, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
31		31
32	# create a port on another node	32	# create a port on another node
33	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
34		34
		35	# destroy a port again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
35	# monitoring	39	# monitoring
36	mon $localport, $cb->(@msg) # callback is invoked on death	40	mon $port, $cb->(@msg) # callback is invoked on death
37	mon $localport, $otherport # kill otherport on abnormal death	41	mon $port, $localport # kill localport on abnormal death
38	mon $localport, $otherport, @msg # send message on death	42	mon $port, $localport, @msg # send message on death
39		43
40	=head1 CURRENT STATUS	44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
41		46
42	bin/aemp - stable.	47	# execute callbacks in $SELF port context
43	AnyEvent::MP - stable API, should work.	48	my $timer = AE::timer 1, 0, psub {
44	AnyEvent::MP::Intro - explains most concepts.	49	die "kill the port, delayed";
45	AnyEvent::MP::Kernel - mostly stable API.	50	};
46	AnyEvent::MP::Global - stable API.	51
		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
		56
		57	# distributed database - queries
		58	db_family $family => $cb->(\%familyhash)
		59	db_keys $family => $cb->(\@keys)
		60	db_values $family => $cb->(\@values)
		61
		62	# distributed database - monitoring a family
		63	db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
47		64
48	=head1 DESCRIPTION	65	=head1 DESCRIPTION
49		66
50	This module (-family) implements a simple message passing framework.	67	This module (-family) implements a simple message passing framework.
51		68
…		…
66		83
67	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
68	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
69	anything was listening for them or not.	86	anything was listening for them or not.
70		87
		88	Ports are represented by (printable) strings called "port IDs".
		89
71	=item port ID - C<nodeid#portname>	90	=item port ID - C<nodeid#portname>
72		91
73	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<#>)
74	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).
75		95
76	=item node	96	=item node
77		97
78	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,
79	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
80	ports.	100	ports.
81		101
82	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
83	(no listening ports). Private nodes cannot talk to other private nodes	103	(no listening ports). Private nodes cannot talk to other private nodes
84	currently.	104	currently, but all nodes can talk to public nodes.
85		105
		106	Nodes is represented by (printable) strings called "node IDs".
		107
86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	108	=item node ID - C<[A-Za-z0-9_\-.:]*>
87		109
88	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
89	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
90	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
91	doesn't interpret node IDs in any way.	113	doesn't interpret node IDs in any way except to uniquely identify a node.
92		114
93	=item binds - C<ip:port>	115	=item binds - C<ip:port>
94		116
95	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
96	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
97	endpoints - binds. Currently, only standard C<ip:port> specifications can	121	Currently, only standard C<ip:port> specifications can be used, which
98	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 thta accepts conenctions form other nodes.
99		124
100	=item seed nodes	125	=item seed nodes
101		126
102	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
103	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
104	network. This node is called a seed.	129	network. These other nodes are called "seed nodes".
105		130
106	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
107	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
108	any node can function as a seed node for others.	133	node for other nodes, and eahc node cna use a different set of seed nodes.
109		134
110	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
111	maintain the network and to connect nodes that otherwise would have	136	maintain the network - all nodes using the same seed node form are part of
112	trouble connecting. They form the backbone of an AnyEvent::MP network.	137	the same network. If a network is split into multiple subnets because e.g.
		138	the network link between the parts goes down, then using the same seed
		139	nodes for all nodes ensures that eventually the subnets get merged again.
113		140
114	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
115	should always be available. They should also be relatively responsive - a	142	should always be available. They should also be relatively responsive - a
116	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.
117		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
118	=item seeds - C<host:port>	154	=item seed IDs - C<host:port>
119		155
120	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
121	TCP port) of nodes that should be used as seed nodes.	157	TCP port) of nodes that should be used as seed nodes.
122		158
123	The nodes listening on those endpoints are expected to be long-running,	159	=item global nodes
124	and at least one of those should always be available. When nodes run out	160
125	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
126	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 makign them the same
		174	reduces overhead).
127		175
128	=back	176	=back
129		177
130	=head1 VARIABLES/FUNCTIONS	178	=head1 VARIABLES/FUNCTIONS
131		179
…		…
133		181
134	=cut	182	=cut
135		183
136	package AnyEvent::MP;	184	package AnyEvent::MP;
137		185
		186	use AnyEvent::MP::Config ();
138	use AnyEvent::MP::Kernel;	187	use AnyEvent::MP::Kernel;
		188	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
139		189
140	use common::sense;	190	use common::sense;
141		191
142	use Carp ();	192	use Carp ();
143		193
144	use AE ();	194	use AnyEvent ();
		195	use Guard ();
145		196
146	use base "Exporter";	197	use base "Exporter";
147		198
148	our $VERSION = 1.21;	199	our $VERSION = $AnyEvent::MP::Config::VERSION;
149		200
150	our @EXPORT = qw(	201	our @EXPORT = qw(
151	NODE $NODE *SELF node_of after	202	NODE $NODE *SELF node_of after
152	configure	203	configure
153	snd rcv mon mon_guard kil psub spawn cal	204	snd rcv mon mon_guard kil psub peval spawn cal
154	port	205	port
		206	db_set db_del db_reg
		207	db_mon db_family db_keys db_values
155	);	208	);
156		209
157	our $SELF;	210	our $SELF;
158		211
159	sub _self_die() {	212	sub _self_die() {
…		…
182	some other nodes in the network to discover other nodes.	235	some other nodes in the network to discover other nodes.
183		236
184	This function configures a node - it must be called exactly once (or	237	This function configures a node - it must be called exactly once (or
185	never) before calling other AnyEvent::MP functions.	238	never) before calling other AnyEvent::MP functions.
186		239
		240	The key/value pairs are basically the same ones as documented for the
		241	F<aemp> command line utility (sans the set/del prefix), with these additions:
		242
		243	=over 4
		244
		245	=item norc => $boolean (default false)
		246
		247	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		248	be consulted - all configuraiton options must be specified in the
		249	C<configure> call.
		250
		251	=item force => $boolean (default false)
		252
		253	IF true, then the values specified in the C<configure> will take
		254	precedence over any values configured via the rc file. The default is for
		255	the rc file to override any options specified in the program.
		256
		257	=back
		258
187	=over 4	259	=over 4
188		260
189	=item step 1, gathering configuration from profiles	261	=item step 1, gathering configuration from profiles
190		262
191	The function first looks up a profile in the aemp configuration (see the	263	The function first looks up a profile in the aemp configuration (see the
…		…
204	That means that the values specified in the profile have highest priority	276	That means that the values specified in the profile have highest priority
205	and the values specified directly via C<configure> have lowest priority,	277	and the values specified directly via C<configure> have lowest priority,
206	and can only be used to specify defaults.	278	and can only be used to specify defaults.
207		279
208	If the profile specifies a node ID, then this will become the node ID of	280	If the profile specifies a node ID, then this will become the node ID of
209	this process. If not, then the profile name will be used as node ID. The	281	this process. If not, then the profile name will be used as node ID, with
210	special node ID of C<anon/> will be replaced by a random node ID.	282	a unique randoms tring (C</%u>) appended.
		283
		284	The node ID can contain some C<%> sequences that are expanded: C<%n>
		285	is expanded to the local nodename, C<%u> is replaced by a random
		286	strign to make the node unique. For example, the F<aemp> commandline
		287	utility uses C<aemp/%n/%u> as nodename, which might expand to
		288	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
211		289
212	=item step 2, bind listener sockets	290	=item step 2, bind listener sockets
213		291
214	The next step is to look up the binds in the profile, followed by binding	292	The next step is to look up the binds in the profile, followed by binding
215	aemp protocol listeners on all binds specified (it is possible and valid	293	aemp protocol listeners on all binds specified (it is possible and valid
…		…
221	used, meaning the node will bind on a dynamically-assigned port on every	299	used, meaning the node will bind on a dynamically-assigned port on every
222	local IP address it finds.	300	local IP address it finds.
223		301
224	=item step 3, connect to seed nodes	302	=item step 3, connect to seed nodes
225		303
226	As the last step, the seeds list from the profile is passed to the	304	As the last step, the seed ID list from the profile is passed to the
227	L<AnyEvent::MP::Global> module, which will then use it to keep	305	L<AnyEvent::MP::Global> module, which will then use it to keep
228	connectivity with at least one node at any point in time.	306	connectivity with at least one node at any point in time.
229		307
230	=back	308	=back
231		309
232	Example: become a distributed node using the local node name as profile.	310	Example: become a distributed node using the local node name as profile.
233	This should be the most common form of invocation for "daemon"-type nodes.	311	This should be the most common form of invocation for "daemon"-type nodes.
234		312
235	configure	313	configure
236		314
237	Example: become an anonymous node. This form is often used for commandline	315	Example: become a semi-anonymous node. This form is often used for
238	clients.	316	commandline clients.
239		317
240	configure nodeid => "anon/";	318	configure nodeid => "myscript/%n/%u";
241		319
242	Example: configure a node using a profile called seed, which si suitable	320	Example: configure a node using a profile called seed, which is suitable
243	for a seed node as it binds on all local addresses on a fixed port (4040,	321	for a seed node as it binds on all local addresses on a fixed port (4040,
244	customary for aemp).	322	customary for aemp).
245		323
246	# use the aemp commandline utility	324	# use the aemp commandline utility
247	# aemp profile seed nodeid anon/ binds '*:4040'	325	# aemp profile seed binds '*:4040'
248		326
249	# then use it	327	# then use it
250	configure profile => "seed";	328	configure profile => "seed";
251		329
252	# or simply use aemp from the shell again:	330	# or simply use aemp from the shell again:
…		…
317		395
318	=cut	396	=cut
319		397
320	sub rcv($@);	398	sub rcv($@);
321		399
322	sub _kilme {	400	my $KILME = sub {
323	die "received message on port without callback";	401	(my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g;
324	}	402	kil $SELF, unhandled_message => "no callback found for message '$tag'";
		403	};
325		404
326	sub port(;&) {	405	sub port(;&) {
327	my $id = "$UNIQ." . $ID++;	406	my $id = $UNIQ . ++$ID;
328	my $port = "$NODE#$id";	407	my $port = "$NODE#$id";
329		408
330	rcv $port, shift \|\| \&_kilme;	409	rcv $port, shift \|\| $KILME;
331		410
332	$port	411	$port
333	}	412	}
334		413
335	=item rcv $local_port, $callback->(@msg)	414	=item rcv $local_port, $callback->(@msg)
…		…
340		419
341	The global C<$SELF> (exported by this module) contains C<$port> while	420	The global C<$SELF> (exported by this module) contains C<$port> while
342	executing the callback. Runtime errors during callback execution will	421	executing the callback. Runtime errors during callback execution will
343	result in the port being C<kil>ed.	422	result in the port being C<kil>ed.
344		423
345	The default callback received all messages not matched by a more specific	424	The default callback receives all messages not matched by a more specific
346	C<tag> match.	425	C<tag> match.
347		426
348	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	427	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349		428
350	Register (or replace) callbacks to be called on messages starting with the	429	Register (or replace) callbacks to be called on messages starting with the
…		…
371	msg1 => sub { ... },	450	msg1 => sub { ... },
372	...	451	...
373	;	452	;
374		453
375	Example: temporarily register a rcv callback for a tag matching some port	454	Example: temporarily register a rcv callback for a tag matching some port
376	(e.g. for a rpc reply) and unregister it after a message was received.	455	(e.g. for an rpc reply) and unregister it after a message was received.
377		456
378	rcv $port, $otherport => sub {	457	rcv $port, $otherport => sub {
379	my @reply = @_;	458	my @reply = @_;
380		459
381	rcv $SELF, $otherport;	460	rcv $SELF, $otherport;
…		…
394	if (ref $_[0]) {	473	if (ref $_[0]) {
395	if (my $self = $PORT_DATA{$portid}) {	474	if (my $self = $PORT_DATA{$portid}) {
396	"AnyEvent::MP::Port" eq ref $self	475	"AnyEvent::MP::Port" eq ref $self
397	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	476	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
398		477
399	$self->[2] = shift;	478	$self->[0] = shift;
400	} else {	479	} else {
401	my $cb = shift;	480	my $cb = shift;
402	$PORT{$portid} = sub {	481	$PORT{$portid} = sub {
403	local $SELF = $port;	482	local $SELF = $port;
404	eval { &$cb }; _self_die if $@;	483	eval { &$cb }; _self_die if $@;
405	};	484	};
406	}	485	}
407	} elsif (defined $_[0]) {	486	} elsif (defined $_[0]) {
408	my $self = $PORT_DATA{$portid} \|\|= do {	487	my $self = $PORT_DATA{$portid} \|\|= do {
409	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	488	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
410		489
411	$PORT{$portid} = sub {	490	$PORT{$portid} = sub {
412	local $SELF = $port;	491	local $SELF = $port;
413		492
414	if (my $cb = $self->[1]{$_[0]}) {	493	if (my $cb = $self->[1]{$_[0]}) {
…		…
436	}	515	}
437		516
438	$port	517	$port
439	}	518	}
440		519
		520	=item peval $port, $coderef[, @args]
		521
		522	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		523	when the code throews an exception the C<$port> will be killed.
		524
		525	Any remaining args will be passed to the callback. Any return values will
		526	be returned to the caller.
		527
		528	This is useful when you temporarily want to execute code in the context of
		529	a port.
		530
		531	Example: create a port and run some initialisation code in it's context.
		532
		533	my $port = port { ... };
		534
		535	peval $port, sub {
		536	init
		537	or die "unable to init";
		538	};
		539
		540	=cut
		541
		542	sub peval($$) {
		543	local $SELF = shift;
		544	my $cb = shift;
		545
		546	if (wantarray) {
		547	my @res = eval { &$cb };
		548	_self_die if $@;
		549	@res
		550	} else {
		551	my $res = eval { &$cb };
		552	_self_die if $@;
		553	$res
		554	}
		555	}
		556
441	=item $closure = psub { BLOCK }	557	=item $closure = psub { BLOCK }
442		558
443	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	559	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
444	closure is executed, sets up the environment in the same way as in C<rcv>	560	closure is executed, sets up the environment in the same way as in C<rcv>
445	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	561	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		562
		563	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		564	BLOCK }, @_ } >>.
446		565
447	This is useful when you register callbacks from C<rcv> callbacks:	566	This is useful when you register callbacks from C<rcv> callbacks:
448		567
449	rcv delayed_reply => sub {	568	rcv delayed_reply => sub {
450	my ($delay, @reply) = @_;	569	my ($delay, @reply) = @_;
…		…
474	$res	593	$res
475	}	594	}
476	}	595	}
477	}	596	}
478		597
		598	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		599
		600	=item $guard = mon $port # kill $SELF when $port dies
		601
479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies	602	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
480
481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
482
483	=item $guard = mon $port # kill $SELF when $port dies
484		603
485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies	604	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
486		605
487	Monitor the given port and do something when the port is killed or	606	Monitor the given port and do something when the port is killed or
488	messages to it were lost, and optionally return a guard that can be used	607	messages to it were lost, and optionally return a guard that can be used
489	to stop monitoring again.	608	to stop monitoring again.
490		609
		610	The first two forms distinguish between "normal" and "abnormal" kil's:
		611
		612	In the first form (another port given), if the C<$port> is C<kil>'ed with
		613	a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the
		614	same reason. That is, on "normal" kil's nothing happens, while under all
		615	other conditions, the other port is killed with the same reason.
		616
		617	The second form (kill self) is the same as the first form, except that
		618	C<$rvport> defaults to C<$SELF>.
		619
		620	The remaining forms don't distinguish between "normal" and "abnormal" kil's
		621	- it's up to the callback or receiver to check whether the C<@reason> is
		622	empty and act accordingly.
		623
491	In the first form (callback), the callback is simply called with any	624	In the third form (callback), the callback is simply called with any
492	number of C<@reason> elements (no @reason means that the port was deleted	625	number of C<@reason> elements (empty @reason means that the port was deleted
493	"normally"). Note also that I<< the callback B<must> never die >>, so use	626	"normally"). Note also that I<< the callback B<must> never die >>, so use
494	C<eval> if unsure.	627	C<eval> if unsure.
495		628
496	In the second form (another port given), the other port (C<$rcvport>)
497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
498	"normal" kils nothing happens, while under all other conditions, the other
499	port is killed with the same reason.
500
501	The third form (kill self) is the same as the second form, except that
502	C<$rvport> defaults to C<$SELF>.
503
504	In the last form (message), a message of the form C<@msg, @reason> will be	629	In the last form (message), a message of the form C<$rcvport, @msg,
505	C<snd>.	630	@reason> will be C<snd>.
506		631
507	Monitoring-actions are one-shot: once messages are lost (and a monitoring	632	Monitoring-actions are one-shot: once messages are lost (and a monitoring
508	alert was raised), they are removed and will not trigger again.	633	alert was raised), they are removed and will not trigger again, even if it
		634	turns out that the port is still alive.
509		635
510	As a rule of thumb, monitoring requests should always monitor a port from	636	As a rule of thumb, monitoring requests should always monitor a remote
511	a local port (or callback). The reason is that kill messages might get	637	port locally (using a local C<$rcvport> or a callback). The reason is that
512	lost, just like any other message. Another less obvious reason is that	638	kill messages might get lost, just like any other message. Another less
513	even monitoring requests can get lost (for example, when the connection	639	obvious reason is that even monitoring requests can get lost (for example,
514	to the other node goes down permanently). When monitoring a port locally	640	when the connection to the other node goes down permanently). When
515	these problems do not exist.	641	monitoring a port locally these problems do not exist.
516		642
517	C<mon> effectively guarantees that, in the absence of hardware failures,	643	C<mon> effectively guarantees that, in the absence of hardware failures,
518	after starting the monitor, either all messages sent to the port will	644	after starting the monitor, either all messages sent to the port will
519	arrive, or the monitoring action will be invoked after possible message	645	arrive, or the monitoring action will be invoked after possible message
520	loss has been detected. No messages will be lost "in between" (after	646	loss has been detected. No messages will be lost "in between" (after
…		…
565	}	691	}
566		692
567	$node->monitor ($port, $cb);	693	$node->monitor ($port, $cb);
568		694
569	defined wantarray	695	defined wantarray
570	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	696	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
571	}	697	}
572		698
573	=item $guard = mon_guard $port, $ref, $ref...	699	=item $guard = mon_guard $port, $ref, $ref...
574		700
575	Monitors the given C<$port> and keeps the passed references. When the port	701	Monitors the given C<$port> and keeps the passed references. When the port
…		…
598		724
599	=item kil $port[, @reason]	725	=item kil $port[, @reason]
600		726
601	Kill the specified port with the given C<@reason>.	727	Kill the specified port with the given C<@reason>.
602		728
603	If no C<@reason> is specified, then the port is killed "normally" (ports	729	If no C<@reason> is specified, then the port is killed "normally" -
604	monitoring other ports will not necessarily die because a port dies	730	monitor callback will be invoked, but the kil will not cause linked ports
605	"normally").	731	(C<mon $mport, $lport> form) to get killed.
606		732
607	Otherwise, linked ports get killed with the same reason (second form of	733	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
608	C<mon>, see above).	734	form) get killed with the same reason.
609		735
610	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	736	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
611	will be reported as reason C<< die => $@ >>.	737	will be reported as reason C<< die => $@ >>.
612		738
613	Transport/communication errors are reported as C<< transport_error =>	739	Transport/communication errors are reported as C<< transport_error =>
614	$message >>.	740	$message >>.
615		741
616	=cut	742	Common idioms:
		743
		744	# silently remove yourself, do not kill linked ports
		745	kil $SELF;
		746
		747	# report a failure in some detail
		748	kil $SELF, failure_mode_1 => "it failed with too high temperature";
		749
		750	# do not waste much time with killing, just die when something goes wrong
		751	open my $fh, "<file"
		752	or die "file: $!";
617		753
618	=item $port = spawn $node, $initfunc[, @initdata]	754	=item $port = spawn $node, $initfunc[, @initdata]
619		755
620	Creates a port on the node C<$node> (which can also be a port ID, in which	756	Creates a port on the node C<$node> (which can also be a port ID, in which
621	case it's the node where that port resides).	757	case it's the node where that port resides).
…		…
679	}	815	}
680		816
681	sub spawn(@) {	817	sub spawn(@) {
682	my ($nodeid, undef) = split /#/, shift, 2;	818	my ($nodeid, undef) = split /#/, shift, 2;
683		819
684	my $id = "$RUNIQ." . $ID++;	820	my $id = $RUNIQ . ++$ID;
685		821
686	$_[0] =~ /::/	822	$_[0] =~ /::/
687	or Carp::croak "spawn init function must be a fully-qualified name, caught";	823	or Carp::croak "spawn init function must be a fully-qualified name, caught";
688		824
689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	825	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
690		826
691	"$nodeid#$id"	827	"$nodeid#$id"
692	}	828	}
		829
693		830
694	=item after $timeout, @msg	831	=item after $timeout, @msg
695		832
696	=item after $timeout, $callback	833	=item after $timeout, $callback
697		834
…		…
712	ref $action[0]	849	ref $action[0]
713	? $action[0]()	850	? $action[0]()
714	: snd @action;	851	: snd @action;
715	};	852	};
716	}	853	}
		854
		855	#=item $cb2 = timeout $seconds, $cb[, @args]
717		856
718	=item cal $port, @msg, $callback[, $timeout]	857	=item cal $port, @msg, $callback[, $timeout]
719		858
720	A simple form of RPC - sends a message to the given C<$port> with the	859	A simple form of RPC - sends a message to the given C<$port> with the
721	given contents (C<@msg>), but adds a reply port to the message.	860	given contents (C<@msg>), but adds a reply port to the message.
…		…
767	$port	906	$port
768	}	907	}
769		908
770	=back	909	=back
771		910
		911	=head1 DISTRIBUTED DATABASE
		912
		913	AnyEvent::MP comes with a simple distributed database. The database will
		914	be mirrored asynchronously on all global nodes. Other nodes bind to one
		915	of the global nodes for their needs. Every node has a "local database"
		916	which contains all the values that are set locally. All local databases
		917	are merged together to form the global database, which can be queried.
		918
		919	The database structure is that of a two-level hash - the database hash
		920	contains hashes which contain values, similarly to a perl hash of hashes,
		921	i.e.:
		922
		923	$DATABASE{$family}{$subkey} = $value
		924
		925	The top level hash key is called "family", and the second-level hash key
		926	is called "subkey" or simply "key".
		927
		928	The family must be alphanumeric, i.e. start with a letter and consist
		929	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		930	pretty much like Perl module names.
		931
		932	As the family namespace is global, it is recommended to prefix family names
		933	with the name of the application or module using it.
		934
		935	The subkeys must be non-empty strings, with no further restrictions.
		936
		937	The values should preferably be strings, but other perl scalars should
		938	work as well (such as C<undef>, arrays and hashes).
		939
		940	Every database entry is owned by one node - adding the same family/subkey
		941	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		942	but the result might be nondeterministic, i.e. the key might have
		943	different values on different nodes.
		944
		945	Different subkeys in the same family can be owned by different nodes
		946	without problems, and in fact, this is the common method to create worker
		947	pools. For example, a worker port for image scaling might do this:
		948
		949	db_set my_image_scalers => $port;
		950
		951	And clients looking for an image scaler will want to get the
		952	C<my_image_scalers> keys from time to time:
		953
		954	db_keys my_image_scalers => sub {
		955	@ports = @{ $_[0] };
		956	};
		957
		958	Or better yet, they want to monitor the database family, so they always
		959	have a reasonable up-to-date copy:
		960
		961	db_mon my_image_scalers => sub {
		962	@ports = keys %{ $_[0] };
		963	};
		964
		965	In general, you can set or delete single subkeys, but query and monitor
		966	whole families only.
		967
		968	If you feel the need to monitor or query a single subkey, try giving it
		969	it's own family.
		970
		971	=over
		972
		973	=item $guard = db_set $family => $subkey [=> $value]
		974
		975	Sets (or replaces) a key to the database - if C<$value> is omitted,
		976	C<undef> is used instead.
		977
		978	When called in non-void context, C<db_set> returns a guard that
		979	automatically calls C<db_del> when it is destroyed.
		980
		981	=item db_del $family => $subkey...
		982
		983	Deletes one or more subkeys from the database family.
		984
		985	=item $guard = db_reg $family => $port => $value
		986
		987	=item $guard = db_reg $family => $port
		988
		989	=item $guard = db_reg $family
		990
		991	Registers a port in the given family and optionally returns a guard to
		992	remove it.
		993
		994	This function basically does the same as:
		995
		996	db_set $family => $port => $value
		997
		998	Except that the port is monitored and automatically removed from the
		999	database family when it is kil'ed.
		1000
		1001	If C<$value> is missing, C<undef> is used. If C<$port> is missing, then
		1002	C<$SELF> is used.
		1003
		1004	This function is most useful to register a port in some port group (which
		1005	is just another name for a database family), and have it removed when the
		1006	port is gone. This works best when the port is a local port.
		1007
		1008	=cut
		1009
		1010	sub db_reg($$;$) {
		1011	my $family = shift;
		1012	my $port = @_ ? shift : $SELF;
		1013
		1014	my $clr = sub { db_del $family => $port };
		1015	mon $port, $clr;
		1016
		1017	db_set $family => $port => $_[0];
		1018
		1019	defined wantarray
		1020	and &Guard::guard ($clr)
		1021	}
		1022
		1023	=item db_family $family => $cb->(\%familyhash)
		1024
		1025	Queries the named database C<$family> and call the callback with the
		1026	family represented as a hash. You can keep and freely modify the hash.
		1027
		1028	=item db_keys $family => $cb->(\@keys)
		1029
		1030	Same as C<db_family>, except it only queries the family I<subkeys> and passes
		1031	them as array reference to the callback.
		1032
		1033	=item db_values $family => $cb->(\@values)
		1034
		1035	Same as C<db_family>, except it only queries the family I<values> and passes them
		1036	as array reference to the callback.
		1037
		1038	=item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
		1039
		1040	Creates a monitor on the given database family. Each time a key is set
		1041	or or is deleted the callback is called with a hash containing the
		1042	database family and three lists of added, changed and deleted subkeys,
		1043	respectively. If no keys have changed then the array reference might be
		1044	C<undef> or even missing.
		1045
		1046	If not called in void context, a guard object is returned that, when
		1047	destroyed, stops the monitor.
		1048
		1049	The family hash reference and the key arrays belong to AnyEvent::MP and
		1050	B<must not be modified or stored> by the callback. When in doubt, make a
		1051	copy.
		1052
		1053	As soon as possible after the monitoring starts, the callback will be
		1054	called with the intiial contents of the family, even if it is empty,
		1055	i.e. there will always be a timely call to the callback with the current
		1056	contents.
		1057
		1058	It is possible that the callback is called with a change event even though
		1059	the subkey is already present and the value has not changed.
		1060
		1061	The monitoring stops when the guard object is destroyed.
		1062
		1063	Example: on every change to the family "mygroup", print out all keys.
		1064
		1065	my $guard = db_mon mygroup => sub {
		1066	my ($family, $a, $c, $d) = @_;
		1067	print "mygroup members: ", (join " ", keys %$family), "\n";
		1068	};
		1069
		1070	Exmaple: wait until the family "My::Module::workers" is non-empty.
		1071
		1072	my $guard; $guard = db_mon My::Module::workers => sub {
		1073	my ($family, $a, $c, $d) = @_;
		1074	return unless %$family;
		1075	undef $guard;
		1076	print "My::Module::workers now nonempty\n";
		1077	};
		1078
		1079	Example: print all changes to the family "AnyRvent::Fantasy::Module".
		1080
		1081	my $guard = db_mon AnyRvent::Fantasy::Module => sub {
		1082	my ($family, $a, $c, $d) = @_;
		1083
		1084	print "+$_=$family->{$_}\n" for @$a;
		1085	print "*$_=$family->{$_}\n" for @$c;
		1086	print "-$_=$family->{$_}\n" for @$d;
		1087	};
		1088
		1089	=cut
		1090
		1091	=back
		1092
772	=head1 AnyEvent::MP vs. Distributed Erlang	1093	=head1 AnyEvent::MP vs. Distributed Erlang
773		1094
774	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1095	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
775	== aemp node, Erlang process == aemp port), so many of the documents and	1096	== aemp node, Erlang process == aemp port), so many of the documents and
776	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	1097	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
807	ports being the special case/exception, where transport errors cannot	1128	ports being the special case/exception, where transport errors cannot
808	occur.	1129	occur.
809		1130
810	=item * Erlang uses processes and a mailbox, AEMP does not queue.	1131	=item * Erlang uses processes and a mailbox, AEMP does not queue.
811		1132
812	Erlang uses processes that selectively receive messages, and therefore	1133	Erlang uses processes that selectively receive messages out of order, and
813	needs a queue. AEMP is event based, queuing messages would serve no	1134	therefore needs a queue. AEMP is event based, queuing messages would serve
814	useful purpose. For the same reason the pattern-matching abilities of	1135	no useful purpose. For the same reason the pattern-matching abilities
815	AnyEvent::MP are more limited, as there is little need to be able to	1136	of AnyEvent::MP are more limited, as there is little need to be able to
816	filter messages without dequeuing them.	1137	filter messages without dequeuing them.
817		1138
818	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	1139	This is not a philosophical difference, but simply stems from AnyEvent::MP
		1140	being event-based, while Erlang is process-based.
		1141
		1142	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		1143	top of AEMP and Coro threads.
819		1144
820	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1145	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
821		1146
822	Sending messages in Erlang is synchronous and blocks the process (and	1147	Sending messages in Erlang is synchronous and blocks the process until
		1148	a conenction has been established and the message sent (and so does not
823	so does not need a queue that can overflow). AEMP sends are immediate,	1149	need a queue that can overflow). AEMP sends return immediately, connection
824	connection establishment is handled in the background.	1150	establishment is handled in the background.
825		1151
826	=item * Erlang suffers from silent message loss, AEMP does not.	1152	=item * Erlang suffers from silent message loss, AEMP does not.
827		1153
828	Erlang implements few guarantees on messages delivery - messages can get	1154	Erlang implements few guarantees on messages delivery - messages can get
829	lost without any of the processes realising it (i.e. you send messages a,	1155	lost without any of the processes realising it (i.e. you send messages a,
830	b, and c, and the other side only receives messages a and c).	1156	b, and c, and the other side only receives messages a and c).
831		1157
832	AEMP guarantees correct ordering, and the guarantee that after one message	1158	AEMP guarantees (modulo hardware errors) correct ordering, and the
833	is lost, all following ones sent to the same port are lost as well, until	1159	guarantee that after one message is lost, all following ones sent to the
834	monitoring raises an error, so there are no silent "holes" in the message	1160	same port are lost as well, until monitoring raises an error, so there are
835	sequence.	1161	no silent "holes" in the message sequence.
		1162
		1163	If you want your software to be very reliable, you have to cope with
		1164	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		1165	simply tries to work better in common error cases, such as when a network
		1166	link goes down.
836		1167
837	=item * Erlang can send messages to the wrong port, AEMP does not.	1168	=item * Erlang can send messages to the wrong port, AEMP does not.
838		1169
839	In Erlang it is quite likely that a node that restarts reuses a process ID	1170	In Erlang it is quite likely that a node that restarts reuses an Erlang
840	known to other nodes for a completely different process, causing messages	1171	process ID known to other nodes for a completely different process,
841	destined for that process to end up in an unrelated process.	1172	causing messages destined for that process to end up in an unrelated
		1173	process.
842		1174
843	AEMP never reuses port IDs, so old messages or old port IDs floating	1175	AEMP does not reuse port IDs, so old messages or old port IDs floating
844	around in the network will not be sent to an unrelated port.	1176	around in the network will not be sent to an unrelated port.
845		1177
846	=item * Erlang uses unprotected connections, AEMP uses secure	1178	=item * Erlang uses unprotected connections, AEMP uses secure
847	authentication and can use TLS.	1179	authentication and can use TLS.
848		1180
…		…
851		1183
852	=item * The AEMP protocol is optimised for both text-based and binary	1184	=item * The AEMP protocol is optimised for both text-based and binary
853	communications.	1185	communications.
854		1186
855	The AEMP protocol, unlike the Erlang protocol, supports both programming	1187	The AEMP protocol, unlike the Erlang protocol, supports both programming
856	language independent text-only protocols (good for debugging) and binary,	1188	language independent text-only protocols (good for debugging), and binary,
857	language-specific serialisers (e.g. Storable). By default, unless TLS is	1189	language-specific serialisers (e.g. Storable). By default, unless TLS is
858	used, the protocol is actually completely text-based.	1190	used, the protocol is actually completely text-based.
859		1191
860	It has also been carefully designed to be implementable in other languages	1192	It has also been carefully designed to be implementable in other languages
861	with a minimum of work while gracefully degrading functionality to make the	1193	with a minimum of work while gracefully degrading functionality to make the
862	protocol simple.	1194	protocol simple.
863		1195
864	=item * AEMP has more flexible monitoring options than Erlang.	1196	=item * AEMP has more flexible monitoring options than Erlang.
865		1197
866	In Erlang, you can chose to receive I<all> exit signals as messages	1198	In Erlang, you can chose to receive I<all> exit signals as messages or
867	or I<none>, there is no in-between, so monitoring single processes is	1199	I<none>, there is no in-between, so monitoring single Erlang processes is
868	difficult to implement. Monitoring in AEMP is more flexible than in	1200	difficult to implement.
869	Erlang, as one can choose between automatic kill, exit message or callback	1201
870	on a per-process basis.	1202	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1203	between automatic kill, exit message or callback on a per-port basis.
871		1204
872	=item * Erlang tries to hide remote/local connections, AEMP does not.	1205	=item * Erlang tries to hide remote/local connections, AEMP does not.
873		1206
874	Monitoring in Erlang is not an indicator of process death/crashes, in the	1207	Monitoring in Erlang is not an indicator of process death/crashes, in the
875	same way as linking is (except linking is unreliable in Erlang).	1208	same way as linking is (except linking is unreliable in Erlang).
…		…
897	overhead, as well as having to keep a proxy object everywhere.	1230	overhead, as well as having to keep a proxy object everywhere.
898		1231
899	Strings can easily be printed, easily serialised etc. and need no special	1232	Strings can easily be printed, easily serialised etc. and need no special
900	procedures to be "valid".	1233	procedures to be "valid".
901		1234
902	And as a result, a miniport consists of a single closure stored in a	1235	And as a result, a port with just a default receiver consists of a single
903	global hash - it can't become much cheaper.	1236	code reference stored in a global hash - it can't become much cheaper.
904		1237
905	=item Why favour JSON, why not a real serialising format such as Storable?	1238	=item Why favour JSON, why not a real serialising format such as Storable?
906		1239
907	In fact, any AnyEvent::MP node will happily accept Storable as framing	1240	In fact, any AnyEvent::MP node will happily accept Storable as framing
908	format, but currently there is no way to make a node use Storable by	1241	format, but currently there is no way to make a node use Storable by
…		…
918	Keeping your messages simple, concentrating on data structures rather than	1251	Keeping your messages simple, concentrating on data structures rather than
919	objects, will keep your messages clean, tidy and efficient.	1252	objects, will keep your messages clean, tidy and efficient.
920		1253
921	=back	1254	=back
922		1255
		1256	=head1 PORTING FROM AnyEvent::MP VERSION 1.X
		1257
		1258	AEMP version 2 has a few major incompatible changes compared to version 1:
		1259
		1260	=over 4
		1261
		1262	=item AnyEvent::MP::Global no longer has group management functions.
		1263
		1264	At least not officially - the grp_* functions are still exported and might
		1265	work, but they will be removed in some later release.
		1266
		1267	AnyEvent::MP now comes with a distributed database that is more
		1268	powerful. Its database families map closely to port groups, but the API
		1269	has changed (the functions are also now exported by AnyEvent::MP). Here is
		1270	a rough porting guide:
		1271
		1272	grp_reg $group, $port # old
		1273	db_reg $group, $port # new
		1274
		1275	$list = grp_get $group # old
		1276	db_keys $group, sub { my $list = shift } # new
		1277
		1278	grp_mon $group, $cb->(\@ports, $add, $del) # old
		1279	db_mon $group, $cb->(\%ports, $add, $change, $del) # new
		1280
		1281	C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is
		1282	no longer instant, because the local node might not have a copy of the
		1283	group. You can either modify your code to allow for a callback, or use
		1284	C<db_mon> to keep an updated copy of the group:
		1285
		1286	my $local_group_copy;
		1287	db_mon $group => sub { $local_group_copy = $_[0] };
		1288
		1289	# now "keys %$local_group_copy" always returns the most up-to-date
		1290	# list of ports in the group.
		1291
		1292	C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon>
		1293	passes a hash as first argument, and an extra C<$chg> argument that can be
		1294	ignored:
		1295
		1296	db_mon $group => sub {
		1297	my ($ports, $add, $chg, $lde) = @_;
		1298	$ports = [keys %$ports];
		1299
		1300	# now $ports, $add and $del are the same as
		1301	# were originally passed by grp_mon.
		1302	...
		1303	};
		1304
		1305	=item Nodes not longer connect to all other nodes.
		1306
		1307	In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global>
		1308	module, which in turn would create connections to all other nodes in the
		1309	network (helped by the seed nodes).
		1310
		1311	In version 2.x, global nodes still connect to all other global nodes, but
		1312	other nodes don't - now every node either is a global node itself, or
		1313	attaches itself to another global node.
		1314
		1315	If a node isn't a global node itself, then it attaches itself to one
		1316	of its seed nodes. If that seed node isn't a global node yet, it will
		1317	automatically be upgraded to a global node.
		1318
		1319	So in many cases, nothing needs to be changed - one just has to make sure
		1320	that all seed nodes are meshed together with the other seed nodes (as with
		1321	AEMP 1.x), and other nodes specify them as seed nodes. This is most easily
		1322	achieved by specifying the same set of seed nodes for all nodes in the
		1323	network.
		1324
		1325	Not opening a connection to every other node is usually an advantage,
		1326	except when you need the lower latency of an already established
		1327	connection. To ensure a node establishes a connection to another node,
		1328	you can monitor the node port (C<mon $node, ...>), which will attempt to
		1329	create the connection (and notify you when the connection fails).
		1330
		1331	=item Listener-less nodes (nodes without binds) are gone.
		1332
		1333	And are not coming back, at least not in their old form. If no C<binds>
		1334	are specified for a node, AnyEvent::MP assumes a default of C<:>.
		1335
		1336	There are vague plans to implement some form of routing domains, which
		1337	might or might not bring back listener-less nodes, but don't count on it.
		1338
		1339	The fact that most connections are now optional somewhat mitigates this,
		1340	as a node can be effectively unreachable from the outside without any
		1341	problems, as long as it isn't a global node and only reaches out to other
		1342	nodes (as opposed to being contacted from other nodes).
		1343
		1344	=item $AnyEvent::MP::Kernel::WARN has gone.
		1345
		1346	AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now
		1347	uses this, and so should your programs.
		1348
		1349	Every module now documents what kinds of messages it generates, with
		1350	AnyEvent::MP acting as a catch all.
		1351
		1352	On the positive side, this means that instead of setting
		1353	C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> -
		1354	much less to type.
		1355
		1356	=back
		1357
		1358	=head1 LOGGING
		1359
		1360	AnyEvent::MP does not normally log anything by itself, but sinc eit is the
		1361	root of the contetx hierarchy for AnyEvent::MP modules, it will receive
		1362	all log messages by submodules.
		1363
923	=head1 SEE ALSO	1364	=head1 SEE ALSO
924		1365
925	L<AnyEvent::MP::Intro> - a gentle introduction.	1366	L<AnyEvent::MP::Intro> - a gentle introduction.
926		1367
927	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1368	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
928		1369
929	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1370	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
930	your applications.	1371	your applications.
		1372
		1373	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
931		1374
932	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1375	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
933	all nodes.	1376	all nodes.
934		1377
935	L<AnyEvent>.	1378	L<AnyEvent>.

Diff Legend

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

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.100 by root, Fri Oct 2 20:41:56 2009 UTC vs. Revision 1.143 by root, Fri Mar 23 17:54:36 2012 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.100 by root, Fri Oct 2 20:41:56 2009 UTC vs.
Revision 1.143 by root, Fri Mar 23 17:54:36 2012 UTC