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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC vs.
Revision 1.133 by root, Mon Mar 12 10:34:06 2012 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
15	# initialise the node so it can send/receive messages	14	# initialise the node so it can send/receive messages
16	initialise_node;	15	configure;
17		16
18	# ports are message endpoints	17	# ports are message destinations
19		18
20	# sending messages	19	# sending messages
21	snd $port, type => data...;	20	snd $port, type => data...;
22	snd $port, @msg;	21	snd $port, @msg;
23	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
24		23
25	# creating/using ports, the simple way	24	# creating/using ports, the simple way
26	my $simple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
27		26
28	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
29	my $port = port;	28	my $port = port;
30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
31	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
32		31
33	# create a port on another node	32	# create a port on another node
34	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
35		34
		35	# destroy a port again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
36	# monitoring	39	# monitoring
37	mon $port, $cb->(@msg) # callback is invoked on death	40	mon $port, $cb->(@msg) # callback is invoked on death
38	mon $port, $otherport # kill otherport on abnormal death	41	mon $port, $localport # kill localport on abnormal death
39	mon $port, $otherport, @msg # send message on death	42	mon $port, $localport, @msg # send message on death
		43
		44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
		46
		47	# execute callbacks in $SELF port context
		48	my $timer = AE::timer 1, 0, psub {
		49	die "kill the port, delayed";
		50	};
40		51
41	=head1 CURRENT STATUS	52	=head1 CURRENT STATUS
42		53
		54	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work	55	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - outdated	56	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable	57	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - mostly stable	58	AnyEvent::MP::Global - stable API.
47	AnyEvent::MP::Node - mostly stable, but internal anyways
48	AnyEvent::MP::Transport - mostly stable, but internal anyways
49
50	stay tuned.
51		59
52	=head1 DESCRIPTION	60	=head1 DESCRIPTION
53		61
54	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
55		63
57	on the same or other hosts, and you can supervise entities remotely.	65	on the same or other hosts, and you can supervise entities remotely.
58		66
59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	67	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60	manual page and the examples under F<eg/>.	68	manual page and the examples under F<eg/>.
61		69
62	At the moment, this module family is a bit underdocumented.
63
64	=head1 CONCEPTS	70	=head1 CONCEPTS
65		71
66	=over 4	72	=over 4
67		73
68	=item port	74	=item port
69		75
70	A port is something you can send messages to (with the C<snd> function).	76	Not to be confused with a TCP port, a "port" is something you can send
		77	messages to (with the C<snd> function).
71		78
72	Ports allow you to register C<rcv> handlers that can match all or just	79	Ports allow you to register C<rcv> handlers that can match all or just
73	some messages. Messages send to ports will not be queued, regardless of	80	some messages. Messages send to ports will not be queued, regardless of
74	anything was listening for them or not.	81	anything was listening for them or not.
75		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
76	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
77		86
78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>)
79	separator, and a port name (a printable string of unspecified format).	88	as separator, and a port name (a printable string of unspecified
		89	format created by AnyEvent::MP).
80		90
81	=item node	91	=item node
82		92
83	A node is a single process containing at least one port - the node port,	93	A node is a single process containing at least one port - the node port,
84	which enables nodes to manage each other remotely, and to create new	94	which enables nodes to manage each other remotely, and to create new
85	ports.	95	ports.
86		96
87	Nodes are either public (have one or more listening ports) or private	97	Nodes are either public (have one or more listening ports) or private
88	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
89	currently.	99	currently, but all nodes can talk to public nodes.
90		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
91	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
92		104
93	A node ID is a string that uniquely identifies the node within a	105	A node ID is a string that uniquely identifies the node within a
94	network. Depending on the configuration used, node IDs can look like a	106	network. Depending on the configuration used, node IDs can look like a
95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	107	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
96	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
97		109
98	=item binds - C<ip:port>	110	=item binds - C<ip:port>
99		111
100	Nodes can only talk to each other by creating some kind of connection to	112	Nodes can only talk to each other by creating some kind of connection to
101	each other. To do this, nodes should listen on one or more local transport	113	each other. To do this, nodes should listen on one or more local transport
		114	endpoints - binds.
		115
102	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
103	be used, which specify TCP ports to listen on.	117	specify TCP ports to listen on. So a bind is basically just a tcp socket
		118	in listening mode thta accepts conenctions form other nodes.
104		119
		120	=item seed nodes
		121
		122	When a node starts, it knows nothing about the network it is in - it
		123	needs to connect to at least one other node that is already in the
		124	network. These other nodes are called "seed nodes".
		125
		126	Seed nodes themselves are not special - they are seed nodes only because
		127	some other node I<uses> them as such, but any node can be used as seed
		128	node for other nodes, and eahc node cna use a different set of seed nodes.
		129
		130	In addition to discovering the network, seed nodes are also used to
		131	maintain the network - all nodes using the same seed node form are part of
		132	the same network. If a network is split into multiple subnets because e.g.
		133	the network link between the parts goes down, then using the same seed
		134	nodes for all nodes ensures that eventually the subnets get merged again.
		135
		136	Seed nodes are expected to be long-running, and at least one seed node
		137	should always be available. They should also be relatively responsive - a
		138	seed node that blocks for long periods will slow down everybody else.
		139
		140	For small networks, it's best if every node uses the same set of seed
		141	nodes. For large networks, it can be useful to specify "regional" seed
		142	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		143	each other. What's important is that all seed nodes connections form a
		144	complete graph, so that the network cannot split into separate subnets
		145	forever.
		146
		147	Seed nodes are represented by seed IDs.
		148
105	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
106		150
107	When a node starts, it knows nothing about the network. To teach the node	151	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
108	about the network it first has to contact some other node within the	152	TCP port) of nodes that should be used as seed nodes.
109	network. This node is called a seed.
110		153
111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	154	=item global nodes
112	are expected to be long-running, and at least one of those should always
113	be available. When nodes run out of connections (e.g. due to a network
114	error), they try to re-establish connections to some seednodes again to
115	join the network.
116		155
117	Apart from being sued for seeding, seednodes are not special in any way -	156	An AEMP network needs a discovery service - nodes need to know how to
118	every public node can be a seednode.	157	connect to other nodes they only know by name. In addition, AEMP offers a
		158	distributed "group database", which maps group names to a list of strings
		159	- for example, to register worker ports.
		160
		161	A network needs at least one global node to work, and allows every node to
		162	be a global node.
		163
		164	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		165	node and tries to keep connections to all other nodes. So while it can
		166	make sense to make every node "global" in small networks, it usually makes
		167	sense to only make seed nodes into global nodes in large networks (nodes
		168	keep connections to seed nodes and global nodes, so makign them the same
		169	reduces overhead).
119		170
120	=back	171	=back
121		172
122	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
123		174
…		…
125		176
126	=cut	177	=cut
127		178
128	package AnyEvent::MP;	179	package AnyEvent::MP;
129		180
		181	use AnyEvent::MP::Config ();
130	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
131		184
132	use common::sense;	185	use common::sense;
133		186
134	use Carp ();	187	use Carp ();
135		188
136	use AE ();	189	use AE ();
		190	use Guard ();
137		191
138	use base "Exporter";	192	use base "Exporter";
139		193
140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	194	our $VERSION = $AnyEvent::MP::Config::VERSION;
141		195
142	our @EXPORT = qw(	196	our @EXPORT = qw(
143	NODE $NODE *SELF node_of after	197	NODE $NODE *SELF node_of after
144	initialise_node	198	configure
145	snd rcv mon mon_guard kil reg psub spawn	199	snd rcv mon mon_guard kil psub peval spawn cal
146	port	200	port
		201	db_set db_del db_reg
		202	db_mon db_family db_keys db_values
147	);	203	);
148		204
149	our $SELF;	205	our $SELF;
150		206
151	sub _self_die() {	207	sub _self_die() {
…		…
156		212
157	=item $thisnode = NODE / $NODE	213	=item $thisnode = NODE / $NODE
158		214
159	The C<NODE> function returns, and the C<$NODE> variable contains, the node	215	The C<NODE> function returns, and the C<$NODE> variable contains, the node
160	ID of the node running in the current process. This value is initialised by	216	ID of the node running in the current process. This value is initialised by
161	a call to C<initialise_node>.	217	a call to C<configure>.
162		218
163	=item $nodeid = node_of $port	219	=item $nodeid = node_of $port
164		220
165	Extracts and returns the node ID from a port ID or a node ID.	221	Extracts and returns the node ID from a port ID or a node ID.
166		222
167	=item initialise_node $profile_name, key => value...	223	=item configure $profile, key => value...
		224
		225	=item configure key => value...
168		226
169	Before a node can talk to other nodes on the network (i.e. enter	227	Before a node can talk to other nodes on the network (i.e. enter
170	"distributed mode") it has to initialise itself - the minimum a node needs	228	"distributed mode") it has to configure itself - the minimum a node needs
171	to know is its own name, and optionally it should know the addresses of	229	to know is its own name, and optionally it should know the addresses of
172	some other nodes in the network to discover other nodes.	230	some other nodes in the network to discover other nodes.
173		231
174	This function initialises a node - it must be called exactly once (or	232	This function configures a node - it must be called exactly once (or
175	never) before calling other AnyEvent::MP functions.	233	never) before calling other AnyEvent::MP functions.
176		234
177	The first argument is a profile name. If it is C<undef> or missing, then	235	The key/value pairs are basically the same ones as documented for the
178	the current nodename will be used instead (i.e. F<uname -n>).	236	F<aemp> command line utility (sans the set/del prefix), with these additions:
179		237
		238	=over 4
		239
		240	=item norc => $boolean (default false)
		241
		242	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		243	be consulted - all configuraiton options must be specified in the
		244	C<configure> call.
		245
		246	=item force => $boolean (default false)
		247
		248	IF true, then the values specified in the C<configure> will take
		249	precedence over any values configured via the rc file. The default is for
		250	the rc file to override any options specified in the program.
		251
		252	=item secure => $pass->($nodeid)
		253
		254	In addition to specifying a boolean, you can specify a code reference that
		255	is called for every remote execution attempt - the execution request is
		256	granted iff the callback returns a true value.
		257
		258	See F<semp setsecure> for more info.
		259
		260	=back
		261
		262	=over 4
		263
		264	=item step 1, gathering configuration from profiles
		265
180	The function first looks up the profile in the aemp configuration (see the	266	The function first looks up a profile in the aemp configuration (see the
181	L<aemp> commandline utility). the profile is calculated as follows:	267	L<aemp> commandline utility). The profile name can be specified via the
		268	named C<profile> parameter or can simply be the first parameter). If it is
		269	missing, then the nodename (F<uname -n>) will be used as profile name.
182		270
		271	The profile data is then gathered as follows:
		272
183	First, all remaining key => value pairs (all of which are conviniently	273	First, all remaining key => value pairs (all of which are conveniently
184	undocumented at the moment) will be used. Then they will be overwritten by	274	undocumented at the moment) will be interpreted as configuration
185	any values specified in the global default configuration (see the F<aemp>	275	data. Then they will be overwritten by any values specified in the global
186	utility), then the chain of profiles selected, if any. That means that	276	default configuration (see the F<aemp> utility), then the chain of
		277	profiles chosen by the profile name (and any C<parent> attributes).
		278
187	the values specified in the profile have highest priority and the values	279	That means that the values specified in the profile have highest priority
188	specified via C<initialise_node> have lowest priority.	280	and the values specified directly via C<configure> have lowest priority,
		281	and can only be used to specify defaults.
189		282
190	If the profile specifies a node ID, then this will become the node ID of	283	If the profile specifies a node ID, then this will become the node ID of
191	this process. If not, then the profile name will be used as node ID. The	284	this process. If not, then the profile name will be used as node ID, with
192	special node ID of C<anon/> will be replaced by a random node ID.	285	a unique randoms tring (C</%u>) appended.
		286
		287	The node ID can contain some C<%> sequences that are expanded: C<%n>
		288	is expanded to the local nodename, C<%u> is replaced by a random
		289	strign to make the node unique. For example, the F<aemp> commandline
		290	utility uses C<aemp/%n/%u> as nodename, which might expand to
		291	C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
		292
		293	=item step 2, bind listener sockets
193		294
194	The next step is to look up the binds in the profile, followed by binding	295	The next step is to look up the binds in the profile, followed by binding
195	aemp protocol listeners on all binds specified (it is possible and valid	296	aemp protocol listeners on all binds specified (it is possible and valid
196	to have no binds, meaning that the node cannot be contacted form the	297	to have no binds, meaning that the node cannot be contacted form the
197	outside. This means the node cannot talk to other nodes that also have no	298	outside. This means the node cannot talk to other nodes that also have no
198	binds, but it can still talk to all "normal" nodes).	299	binds, but it can still talk to all "normal" nodes).
199		300
200	If the profile does not specify a binds list, then a default of C<*> is	301	If the profile does not specify a binds list, then a default of C<*> is
201	used.	302	used, meaning the node will bind on a dynamically-assigned port on every
		303	local IP address it finds.
202		304
		305	=item step 3, connect to seed nodes
		306
203	Lastly, the seeds list from the profile is passed to the	307	As the last step, the seed ID list from the profile is passed to the
204	L<AnyEvent::MP::Global> module, which will then use it to keep	308	L<AnyEvent::MP::Global> module, which will then use it to keep
205	connectivity with at least on of those seed nodes at any point in time.	309	connectivity with at least one node at any point in time.
206		310
207	Example: become a distributed node listening on the guessed noderef, or	311	=back
208	the one specified via C<aemp> for the current node. This should be the	312
		313	Example: become a distributed node using the local node name as profile.
209	most common form of invocation for "daemon"-type nodes.	314	This should be the most common form of invocation for "daemon"-type nodes.
210		315
211	initialise_node;	316	configure
212		317
213	Example: become an anonymous node. This form is often used for commandline	318	Example: become a semi-anonymous node. This form is often used for
214	clients.	319	commandline clients.
215		320
216	initialise_node "anon/";	321	configure nodeid => "myscript/%n/%u";
217		322
218	Example: become a distributed node. If there is no profile of the given	323	Example: configure a node using a profile called seed, which is suitable
219	name, or no binds list was specified, resolve C<localhost:4044> and bind	324	for a seed node as it binds on all local addresses on a fixed port (4040,
220	on the resulting addresses.	325	customary for aemp).
221		326
222	initialise_node "localhost:4044";	327	# use the aemp commandline utility
		328	# aemp profile seed binds '*:4040'
		329
		330	# then use it
		331	configure profile => "seed";
		332
		333	# or simply use aemp from the shell again:
		334	# aemp run profile seed
		335
		336	# or provide a nicer-to-remember nodeid
		337	# aemp run profile seed nodeid "$(hostname)"
223		338
224	=item $SELF	339	=item $SELF
225		340
226	Contains the current port id while executing C<rcv> callbacks or C<psub>	341	Contains the current port id while executing C<rcv> callbacks or C<psub>
227	blocks.	342	blocks.
…		…
283		398
284	=cut	399	=cut
285		400
286	sub rcv($@);	401	sub rcv($@);
287		402
288	sub _kilme {	403	my $KILME = sub {
289	die "received message on port without callback";	404	(my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g;
290	}	405	kil $SELF, unhandled_message => "no callback set for message (first element $tag)";
		406	};
291		407
292	sub port(;&) {	408	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	409	my $id = $UNIQ . ++$ID;
294	my $port = "$NODE#$id";	410	my $port = "$NODE#$id";
295		411
296	rcv $port, shift \|\| \&_kilme;	412	rcv $port, shift \|\| $KILME;
297		413
298	$port	414	$port
299	}	415	}
300		416
301	=item rcv $local_port, $callback->(@msg)	417	=item rcv $local_port, $callback->(@msg)
…		…
306		422
307	The global C<$SELF> (exported by this module) contains C<$port> while	423	The global C<$SELF> (exported by this module) contains C<$port> while
308	executing the callback. Runtime errors during callback execution will	424	executing the callback. Runtime errors during callback execution will
309	result in the port being C<kil>ed.	425	result in the port being C<kil>ed.
310		426
311	The default callback received all messages not matched by a more specific	427	The default callback receives all messages not matched by a more specific
312	C<tag> match.	428	C<tag> match.
313		429
314	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	430	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
315		431
316	Register (or replace) callbacks to be called on messages starting with the	432	Register (or replace) callbacks to be called on messages starting with the
…		…
337	msg1 => sub { ... },	453	msg1 => sub { ... },
338	...	454	...
339	;	455	;
340		456
341	Example: temporarily register a rcv callback for a tag matching some port	457	Example: temporarily register a rcv callback for a tag matching some port
342	(e.g. for a rpc reply) and unregister it after a message was received.	458	(e.g. for an rpc reply) and unregister it after a message was received.
343		459
344	rcv $port, $otherport => sub {	460	rcv $port, $otherport => sub {
345	my @reply = @_;	461	my @reply = @_;
346		462
347	rcv $SELF, $otherport;	463	rcv $SELF, $otherport;
…		…
349		465
350	=cut	466	=cut
351		467
352	sub rcv($@) {	468	sub rcv($@) {
353	my $port = shift;	469	my $port = shift;
354	my ($noderef, $portid) = split /#/, $port, 2;	470	my ($nodeid, $portid) = split /#/, $port, 2;
355		471
356	$NODE{$noderef} == $NODE{""}	472	$NODE{$nodeid} == $NODE{""}
357	or Carp::croak "$port: rcv can only be called on local ports, caught";	473	or Carp::croak "$port: rcv can only be called on local ports, caught";
358		474
359	while (@_) {	475	while (@_) {
360	if (ref $_[0]) {	476	if (ref $_[0]) {
361	if (my $self = $PORT_DATA{$portid}) {	477	if (my $self = $PORT_DATA{$portid}) {
362	"AnyEvent::MP::Port" eq ref $self	478	"AnyEvent::MP::Port" eq ref $self
363	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	479	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
364		480
365	$self->[2] = shift;	481	$self->[0] = shift;
366	} else {	482	} else {
367	my $cb = shift;	483	my $cb = shift;
368	$PORT{$portid} = sub {	484	$PORT{$portid} = sub {
369	local $SELF = $port;	485	local $SELF = $port;
370	eval { &$cb }; _self_die if $@;	486	eval { &$cb }; _self_die if $@;
371	};	487	};
372	}	488	}
373	} elsif (defined $_[0]) {	489	} elsif (defined $_[0]) {
374	my $self = $PORT_DATA{$portid} \|\|= do {	490	my $self = $PORT_DATA{$portid} \|\|= do {
375	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	491	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
376		492
377	$PORT{$portid} = sub {	493	$PORT{$portid} = sub {
378	local $SELF = $port;	494	local $SELF = $port;
379		495
380	if (my $cb = $self->[1]{$_[0]}) {	496	if (my $cb = $self->[1]{$_[0]}) {
…		…
402	}	518	}
403		519
404	$port	520	$port
405	}	521	}
406		522
		523	=item peval $port, $coderef[, @args]
		524
		525	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		526	when the code throews an exception the C<$port> will be killed.
		527
		528	Any remaining args will be passed to the callback. Any return values will
		529	be returned to the caller.
		530
		531	This is useful when you temporarily want to execute code in the context of
		532	a port.
		533
		534	Example: create a port and run some initialisation code in it's context.
		535
		536	my $port = port { ... };
		537
		538	peval $port, sub {
		539	init
		540	or die "unable to init";
		541	};
		542
		543	=cut
		544
		545	sub peval($$) {
		546	local $SELF = shift;
		547	my $cb = shift;
		548
		549	if (wantarray) {
		550	my @res = eval { &$cb };
		551	_self_die if $@;
		552	@res
		553	} else {
		554	my $res = eval { &$cb };
		555	_self_die if $@;
		556	$res
		557	}
		558	}
		559
407	=item $closure = psub { BLOCK }	560	=item $closure = psub { BLOCK }
408		561
409	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	562	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
410	closure is executed, sets up the environment in the same way as in C<rcv>	563	closure is executed, sets up the environment in the same way as in C<rcv>
411	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	564	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		565
		566	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		567	BLOCK }, @_ } >>.
412		568
413	This is useful when you register callbacks from C<rcv> callbacks:	569	This is useful when you register callbacks from C<rcv> callbacks:
414		570
415	rcv delayed_reply => sub {	571	rcv delayed_reply => sub {
416	my ($delay, @reply) = @_;	572	my ($delay, @reply) = @_;
…		…
452		608
453	Monitor the given port and do something when the port is killed or	609	Monitor the given port and do something when the port is killed or
454	messages to it were lost, and optionally return a guard that can be used	610	messages to it were lost, and optionally return a guard that can be used
455	to stop monitoring again.	611	to stop monitoring again.
456		612
		613	In the first form (callback), the callback is simply called with any
		614	number of C<@reason> elements (no @reason means that the port was deleted
		615	"normally"). Note also that I<< the callback B<must> never die >>, so use
		616	C<eval> if unsure.
		617
		618	In the second form (another port given), the other port (C<$rcvport>)
		619	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		620	"normal" kils nothing happens, while under all other conditions, the other
		621	port is killed with the same reason.
		622
		623	The third form (kill self) is the same as the second form, except that
		624	C<$rvport> defaults to C<$SELF>.
		625
		626	In the last form (message), a message of the form C<@msg, @reason> will be
		627	C<snd>.
		628
		629	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		630	alert was raised), they are removed and will not trigger again.
		631
		632	As a rule of thumb, monitoring requests should always monitor a port from
		633	a local port (or callback). The reason is that kill messages might get
		634	lost, just like any other message. Another less obvious reason is that
		635	even monitoring requests can get lost (for example, when the connection
		636	to the other node goes down permanently). When monitoring a port locally
		637	these problems do not exist.
		638
457	C<mon> effectively guarantees that, in the absence of hardware failures,	639	C<mon> effectively guarantees that, in the absence of hardware failures,
458	after starting the monitor, either all messages sent to the port will	640	after starting the monitor, either all messages sent to the port will
459	arrive, or the monitoring action will be invoked after possible message	641	arrive, or the monitoring action will be invoked after possible message
460	loss has been detected. No messages will be lost "in between" (after	642	loss has been detected. No messages will be lost "in between" (after
461	the first lost message no further messages will be received by the	643	the first lost message no further messages will be received by the
462	port). After the monitoring action was invoked, further messages might get	644	port). After the monitoring action was invoked, further messages might get
463	delivered again.	645	delivered again.
464		646
465	Note that monitoring-actions are one-shot: once messages are lost (and a	647	Inter-host-connection timeouts and monitoring depend on the transport
466	monitoring alert was raised), they are removed and will not trigger again.	648	used. The only transport currently implemented is TCP, and AnyEvent::MP
		649	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		650	non-idle connection, and usually around two hours for idle connections).
467		651
468	In the first form (callback), the callback is simply called with any	652	This means that monitoring is good for program errors and cleaning up
469	number of C<@reason> elements (no @reason means that the port was deleted	653	stuff eventually, but they are no replacement for a timeout when you need
470	"normally"). Note also that I<< the callback B<must> never die >>, so use	654	to ensure some maximum latency.
471	C<eval> if unsure.
472
473	In the second form (another port given), the other port (C<$rcvport>)
474	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
475	"normal" kils nothing happens, while under all other conditions, the other
476	port is killed with the same reason.
477
478	The third form (kill self) is the same as the second form, except that
479	C<$rvport> defaults to C<$SELF>.
480
481	In the last form (message), a message of the form C<@msg, @reason> will be
482	C<snd>.
483
484	As a rule of thumb, monitoring requests should always monitor a port from
485	a local port (or callback). The reason is that kill messages might get
486	lost, just like any other message. Another less obvious reason is that
487	even monitoring requests can get lost (for exmaple, when the connection
488	to the other node goes down permanently). When monitoring a port locally
489	these problems do not exist.
490		655
491	Example: call a given callback when C<$port> is killed.	656	Example: call a given callback when C<$port> is killed.
492		657
493	mon $port, sub { warn "port died because of <@_>\n" };	658	mon $port, sub { warn "port died because of <@_>\n" };
494		659
…		…
501	mon $port, $self => "restart";	666	mon $port, $self => "restart";
502		667
503	=cut	668	=cut
504		669
505	sub mon {	670	sub mon {
506	my ($noderef, $port) = split /#/, shift, 2;	671	my ($nodeid, $port) = split /#/, shift, 2;
507		672
508	my $node = $NODE{$noderef} \|\| add_node $noderef;	673	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
509		674
510	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	675	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
511		676
512	unless (ref $cb) {	677	unless (ref $cb) {
513	if (@_) {	678	if (@_) {
…		…
522	}	687	}
523		688
524	$node->monitor ($port, $cb);	689	$node->monitor ($port, $cb);
525		690
526	defined wantarray	691	defined wantarray
527	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	692	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
528	}	693	}
529		694
530	=item $guard = mon_guard $port, $ref, $ref...	695	=item $guard = mon_guard $port, $ref, $ref...
531		696
532	Monitors the given C<$port> and keeps the passed references. When the port	697	Monitors the given C<$port> and keeps the passed references. When the port
…		…
555		720
556	=item kil $port[, @reason]	721	=item kil $port[, @reason]
557		722
558	Kill the specified port with the given C<@reason>.	723	Kill the specified port with the given C<@reason>.
559		724
560	If no C<@reason> is specified, then the port is killed "normally" (ports	725	If no C<@reason> is specified, then the port is killed "normally" -
561	monitoring other ports will not necessarily die because a port dies	726	monitor callback will be invoked, but the kil will not cause linked ports
562	"normally").	727	(C<mon $mport, $lport> form) to get killed.
563		728
564	Otherwise, linked ports get killed with the same reason (second form of	729	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
565	C<mon>, see above).	730	form) get killed with the same reason.
566		731
567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	732	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
568	will be reported as reason C<< die => $@ >>.	733	will be reported as reason C<< die => $@ >>.
569		734
570	Transport/communication errors are reported as C<< transport_error =>	735	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	736	$message >>.
572		737
573	=cut	738	Common idioms:
		739
		740	# silently remove yourself, do not kill linked ports
		741	kil $SELF;
		742
		743	# report a failure in some detail
		744	kil $SELF, failure_mode_1 => "it failed with too high temperature";
		745
		746	# do not waste much time with killing, just die when something goes wrong
		747	open my $fh, "<file"
		748	or die "file: $!";
574		749
575	=item $port = spawn $node, $initfunc[, @initdata]	750	=item $port = spawn $node, $initfunc[, @initdata]
576		751
577	Creates a port on the node C<$node> (which can also be a port ID, in which	752	Creates a port on the node C<$node> (which can also be a port ID, in which
578	case it's the node where that port resides).	753	case it's the node where that port resides).
…		…
589	the package, then the package above the package and so on (e.g.	764	the package, then the package above the package and so on (e.g.
590	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	765	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
591	exists or it runs out of package names.	766	exists or it runs out of package names.
592		767
593	The init function is then called with the newly-created port as context	768	The init function is then called with the newly-created port as context
594	object (C<$SELF>) and the C<@initdata> values as arguments.	769	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		770	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		771	the port might not get created.
595		772
596	A common idiom is to pass a local port, immediately monitor the spawned	773	A common idiom is to pass a local port, immediately monitor the spawned
597	port, and in the remote init function, immediately monitor the passed	774	port, and in the remote init function, immediately monitor the passed
598	local port. This two-way monitoring ensures that both ports get cleaned up	775	local port. This two-way monitoring ensures that both ports get cleaned up
599	when there is a problem.	776	when there is a problem.
600		777
		778	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		779	caller before C<spawn> returns (by delaying invocation when spawn is
		780	called for the local node).
		781
601	Example: spawn a chat server port on C<$othernode>.	782	Example: spawn a chat server port on C<$othernode>.
602		783
603	# this node, executed from within a port context:	784	# this node, executed from within a port context:
604	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	785	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
605	mon $server;	786	mon $server;
…		…
619		800
620	sub _spawn {	801	sub _spawn {
621	my $port = shift;	802	my $port = shift;
622	my $init = shift;	803	my $init = shift;
623		804
		805	# rcv will create the actual port
624	local $SELF = "$NODE#$port";	806	local $SELF = "$NODE#$port";
625	eval {	807	eval {
626	&{ load_func $init }	808	&{ load_func $init }
627	};	809	};
628	_self_die if $@;	810	_self_die if $@;
629	}	811	}
630		812
631	sub spawn(@) {	813	sub spawn(@) {
632	my ($noderef, undef) = split /#/, shift, 2;	814	my ($nodeid, undef) = split /#/, shift, 2;
633		815
634	my $id = "$RUNIQ." . $ID++;	816	my $id = $RUNIQ . ++$ID;
635		817
636	$_[0] =~ /::/	818	$_[0] =~ /::/
637	or Carp::croak "spawn init function must be a fully-qualified name, caught";	819	or Carp::croak "spawn init function must be a fully-qualified name, caught";
638		820
639	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	821	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
640		822
641	"$noderef#$id"	823	"$nodeid#$id"
642	}	824	}
		825
643		826
644	=item after $timeout, @msg	827	=item after $timeout, @msg
645		828
646	=item after $timeout, $callback	829	=item after $timeout, $callback
647		830
…		…
663	? $action[0]()	846	? $action[0]()
664	: snd @action;	847	: snd @action;
665	};	848	};
666	}	849	}
667		850
		851	#=item $cb2 = timeout $seconds, $cb[, @args]
		852
		853	=item cal $port, @msg, $callback[, $timeout]
		854
		855	A simple form of RPC - sends a message to the given C<$port> with the
		856	given contents (C<@msg>), but adds a reply port to the message.
		857
		858	The reply port is created temporarily just for the purpose of receiving
		859	the reply, and will be C<kil>ed when no longer needed.
		860
		861	A reply message sent to the port is passed to the C<$callback> as-is.
		862
		863	If an optional time-out (in seconds) is given and it is not C<undef>,
		864	then the callback will be called without any arguments after the time-out
		865	elapsed and the port is C<kil>ed.
		866
		867	If no time-out is given (or it is C<undef>), then the local port will
		868	monitor the remote port instead, so it eventually gets cleaned-up.
		869
		870	Currently this function returns the temporary port, but this "feature"
		871	might go in future versions unless you can make a convincing case that
		872	this is indeed useful for something.
		873
		874	=cut
		875
		876	sub cal(@) {
		877	my $timeout = ref $_[-1] ? undef : pop;
		878	my $cb = pop;
		879
		880	my $port = port {
		881	undef $timeout;
		882	kil $SELF;
		883	&$cb;
		884	};
		885
		886	if (defined $timeout) {
		887	$timeout = AE::timer $timeout, 0, sub {
		888	undef $timeout;
		889	kil $port;
		890	$cb->();
		891	};
		892	} else {
		893	mon $_[0], sub {
		894	kil $port;
		895	$cb->();
		896	};
		897	}
		898
		899	push @_, $port;
		900	&snd;
		901
		902	$port
		903	}
		904
		905	=back
		906
		907	=head1 DISTRIBUTED DATABASE
		908
		909	AnyEvent::MP comes with a simple distributed database. The database will
		910	be mirrored asynchronously on all global nodes. Other nodes bind to one
		911	of the global nodes for their needs. Every node has a "local database"
		912	which contains all the values that are set locally. All local databases
		913	are merged together to form the global database, which can be queried.
		914
		915	The database structure is that of a two-level hash - the database hash
		916	contains hashes which contain values, similarly to a perl hash of hashes,
		917	i.e.:
		918
		919	$DATABASE{$family}{$subkey} = $value
		920
		921	The top level hash key is called "family", and the second-level hash key
		922	is called "subkey" or simply "key".
		923
		924	The family must be alphanumeric, i.e. start with a letter and consist
		925	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		926	pretty much like Perl module names.
		927
		928	As the family namespace is global, it is recommended to prefix family names
		929	with the name of the application or module using it.
		930
		931	The subkeys must be non-empty strings, with no further restrictions.
		932
		933	The values should preferably be strings, but other perl scalars should
		934	work as well (such as C<undef>, arrays and hashes).
		935
		936	Every database entry is owned by one node - adding the same family/subkey
		937	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		938	but the result might be nondeterministic, i.e. the key might have
		939	different values on different nodes.
		940
		941	Different subkeys in the same family can be owned by different nodes
		942	without problems, and in fact, this is the common method to create worker
		943	pools. For example, a worker port for image scaling might do this:
		944
		945	db_set my_image_scalers => $port;
		946
		947	And clients looking for an image scaler will want to get the
		948	C<my_image_scalers> keys from time to time:
		949
		950	db_keys my_image_scalers => sub {
		951	@ports = @{ $_[0] };
		952	};
		953
		954	Or better yet, they want to monitor the database family, so they always
		955	have a reasonable up-to-date copy:
		956
		957	db_mon my_image_scalers => sub {
		958	@ports = keys %{ $_[0] };
		959	};
		960
		961	In general, you can set or delete single subkeys, but query and monitor
		962	whole families only.
		963
		964	If you feel the need to monitor or query a single subkey, try giving it
		965	it's own family.
		966
		967	=over
		968
		969	=item db_set $family => $subkey [=> $value]
		970
		971	Sets (or replaces) a key to the database - if C<$value> is omitted,
		972	C<undef> is used instead.
		973
		974	=item db_del $family => $subkey...
		975
		976	Deletes one or more subkeys from the database family.
		977
		978	=item $guard = db_reg $family => $subkey [=> $value]
		979
		980	Sets the key on the database and returns a guard. When the guard is
		981	destroyed, the key is deleted from the database. If C<$value> is missing,
		982	then C<undef> is used.
		983
		984	=item db_family $family => $cb->(\%familyhash)
		985
		986	Queries the named database C<$family> and call the callback with the
		987	family represented as a hash. You can keep and freely modify the hash.
		988
		989	=item db_keys $family => $cb->(\@keys)
		990
		991	Same as C<db_family>, except it only queries the family I<subkeys> and passes
		992	them as array reference to the callback.
		993
		994	=item db_values $family => $cb->(\@values)
		995
		996	Same as C<db_family>, except it only queries the family I<values> and passes them
		997	as array reference to the callback.
		998
		999	=item $guard = db_mon $family => $cb->($familyhash, \@added, \@changed, \@deleted)
		1000
		1001	Creates a monitor on the given database family. Each time a key is set
		1002	or or is deleted the callback is called with a hash containing the
		1003	database family and three lists of added, changed and deleted subkeys,
		1004	respectively. If no keys have changed then the array reference might be
		1005	C<undef> or even missing.
		1006
		1007	If not called in void context, a guard object is returned that, when
		1008	destroyed, stops the monitor.
		1009
		1010	The family hash reference and the key arrays belong to AnyEvent::MP and
		1011	B<must not be modified or stored> by the callback. When in doubt, make a
		1012	copy.
		1013
		1014	As soon as possible after the monitoring starts, the callback will be
		1015	called with the intiial contents of the family, even if it is empty,
		1016	i.e. there will always be a timely call to the callback with the current
		1017	contents.
		1018
		1019	It is possible that the callback is called with a change event even though
		1020	the subkey is already present and the value has not changed.
		1021
		1022	The monitoring stops when the guard object is destroyed.
		1023
		1024	Example: on every change to the family "mygroup", print out all keys.
		1025
		1026	my $guard = db_mon mygroup => sub {
		1027	my ($family, $a, $c, $d) = @_;
		1028	print "mygroup members: ", (join " ", keys %$family), "\n";
		1029	};
		1030
		1031	Exmaple: wait until the family "My::Module::workers" is non-empty.
		1032
		1033	my $guard; $guard = db_mon My::Module::workers => sub {
		1034	my ($family, $a, $c, $d) = @_;
		1035	return unless %$family;
		1036	undef $guard;
		1037	print "My::Module::workers now nonempty\n";
		1038	};
		1039
		1040	Example: print all changes to the family "AnyRvent::Fantasy::Module".
		1041
		1042	my $guard = db_mon AnyRvent::Fantasy::Module => sub {
		1043	my ($family, $a, $c, $d) = @_;
		1044
		1045	print "+$_=$family->{$_}\n" for @$a;
		1046	print "*$_=$family->{$_}\n" for @$c;
		1047	print "-$_=$family->{$_}\n" for @$d;
		1048	};
		1049
		1050	=cut
		1051
668	=back	1052	=back
669		1053
670	=head1 AnyEvent::MP vs. Distributed Erlang	1054	=head1 AnyEvent::MP vs. Distributed Erlang
671		1055
672	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	1056	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
673	== aemp node, Erlang process == aemp port), so many of the documents and	1057	== aemp node, Erlang process == aemp port), so many of the documents and
674	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	1058	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
675	sample:	1059	sample:
676		1060
677	http://www.Erlang.se/doc/programming_rules.shtml	1061	http://www.erlang.se/doc/programming_rules.shtml
678	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	1062	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
679	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	1063	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
680	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	1064	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
681		1065
682	Despite the similarities, there are also some important differences:	1066	Despite the similarities, there are also some important differences:
683		1067
684	=over 4	1068	=over 4
685		1069
686	=item * Node IDs are arbitrary strings in AEMP.	1070	=item * Node IDs are arbitrary strings in AEMP.
687		1071
688	Erlang relies on special naming and DNS to work everywhere in the same	1072	Erlang relies on special naming and DNS to work everywhere in the same
689	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	1073	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
690	configuraiton or DNS), but will otherwise discover other odes itself.	1074	configuration or DNS), and possibly the addresses of some seed nodes, but
		1075	will otherwise discover other nodes (and their IDs) itself.
691		1076
692	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	1077	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
693	uses "local ports are like remote ports".	1078	uses "local ports are like remote ports".
694		1079
695	The failure modes for local ports are quite different (runtime errors	1080	The failure modes for local ports are quite different (runtime errors
…		…
704	ports being the special case/exception, where transport errors cannot	1089	ports being the special case/exception, where transport errors cannot
705	occur.	1090	occur.
706		1091
707	=item * Erlang uses processes and a mailbox, AEMP does not queue.	1092	=item * Erlang uses processes and a mailbox, AEMP does not queue.
708		1093
709	Erlang uses processes that selectively receive messages, and therefore	1094	Erlang uses processes that selectively receive messages out of order, and
710	needs a queue. AEMP is event based, queuing messages would serve no	1095	therefore needs a queue. AEMP is event based, queuing messages would serve
711	useful purpose. For the same reason the pattern-matching abilities of	1096	no useful purpose. For the same reason the pattern-matching abilities
712	AnyEvent::MP are more limited, as there is little need to be able to	1097	of AnyEvent::MP are more limited, as there is little need to be able to
713	filter messages without dequeing them.	1098	filter messages without dequeuing them.
714		1099
715	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	1100	This is not a philosophical difference, but simply stems from AnyEvent::MP
		1101	being event-based, while Erlang is process-based.
		1102
		1103	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		1104	top of AEMP and Coro threads.
716		1105
717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1106	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
718		1107
719	Sending messages in Erlang is synchronous and blocks the process (and	1108	Sending messages in Erlang is synchronous and blocks the process until
		1109	a conenction has been established and the message sent (and so does not
720	so does not need a queue that can overflow). AEMP sends are immediate,	1110	need a queue that can overflow). AEMP sends return immediately, connection
721	connection establishment is handled in the background.	1111	establishment is handled in the background.
722		1112
723	=item * Erlang suffers from silent message loss, AEMP does not.	1113	=item * Erlang suffers from silent message loss, AEMP does not.
724		1114
725	Erlang makes few guarantees on messages delivery - messages can get lost	1115	Erlang implements few guarantees on messages delivery - messages can get
726	without any of the processes realising it (i.e. you send messages a, b,	1116	lost without any of the processes realising it (i.e. you send messages a,
727	and c, and the other side only receives messages a and c).	1117	b, and c, and the other side only receives messages a and c).
728		1118
729	AEMP guarantees correct ordering, and the guarantee that after one message	1119	AEMP guarantees (modulo hardware errors) correct ordering, and the
730	is lost, all following ones sent to the same port are lost as well, until	1120	guarantee that after one message is lost, all following ones sent to the
731	monitoring raises an error, so there are no silent "holes" in the message	1121	same port are lost as well, until monitoring raises an error, so there are
732	sequence.	1122	no silent "holes" in the message sequence.
		1123
		1124	If you want your software to be very reliable, you have to cope with
		1125	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		1126	simply tries to work better in common error cases, such as when a network
		1127	link goes down.
733		1128
734	=item * Erlang can send messages to the wrong port, AEMP does not.	1129	=item * Erlang can send messages to the wrong port, AEMP does not.
735		1130
736	In Erlang it is quite likely that a node that restarts reuses a process ID	1131	In Erlang it is quite likely that a node that restarts reuses an Erlang
737	known to other nodes for a completely different process, causing messages	1132	process ID known to other nodes for a completely different process,
738	destined for that process to end up in an unrelated process.	1133	causing messages destined for that process to end up in an unrelated
		1134	process.
739		1135
740	AEMP never reuses port IDs, so old messages or old port IDs floating	1136	AEMP does not reuse port IDs, so old messages or old port IDs floating
741	around in the network will not be sent to an unrelated port.	1137	around in the network will not be sent to an unrelated port.
742		1138
743	=item * Erlang uses unprotected connections, AEMP uses secure	1139	=item * Erlang uses unprotected connections, AEMP uses secure
744	authentication and can use TLS.	1140	authentication and can use TLS.
745		1141
…		…
748		1144
749	=item * The AEMP protocol is optimised for both text-based and binary	1145	=item * The AEMP protocol is optimised for both text-based and binary
750	communications.	1146	communications.
751		1147
752	The AEMP protocol, unlike the Erlang protocol, supports both programming	1148	The AEMP protocol, unlike the Erlang protocol, supports both programming
753	language independent text-only protocols (good for debugging) and binary,	1149	language independent text-only protocols (good for debugging), and binary,
754	language-specific serialisers (e.g. Storable). By default, unless TLS is	1150	language-specific serialisers (e.g. Storable). By default, unless TLS is
755	used, the protocol is actually completely text-based.	1151	used, the protocol is actually completely text-based.
756		1152
757	It has also been carefully designed to be implementable in other languages	1153	It has also been carefully designed to be implementable in other languages
758	with a minimum of work while gracefully degrading functionality to make the	1154	with a minimum of work while gracefully degrading functionality to make the
759	protocol simple.	1155	protocol simple.
760		1156
761	=item * AEMP has more flexible monitoring options than Erlang.	1157	=item * AEMP has more flexible monitoring options than Erlang.
762		1158
763	In Erlang, you can chose to receive I<all> exit signals as messages	1159	In Erlang, you can chose to receive I<all> exit signals as messages or
764	or I<none>, there is no in-between, so monitoring single processes is	1160	I<none>, there is no in-between, so monitoring single Erlang processes is
765	difficult to implement. Monitoring in AEMP is more flexible than in	1161	difficult to implement.
766	Erlang, as one can choose between automatic kill, exit message or callback	1162
767	on a per-process basis.	1163	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1164	between automatic kill, exit message or callback on a per-port basis.
768		1165
769	=item * Erlang tries to hide remote/local connections, AEMP does not.	1166	=item * Erlang tries to hide remote/local connections, AEMP does not.
770		1167
771	Monitoring in Erlang is not an indicator of process death/crashes, in the	1168	Monitoring in Erlang is not an indicator of process death/crashes, in the
772	same way as linking is (except linking is unreliable in Erlang).	1169	same way as linking is (except linking is unreliable in Erlang).
…		…
794	overhead, as well as having to keep a proxy object everywhere.	1191	overhead, as well as having to keep a proxy object everywhere.
795		1192
796	Strings can easily be printed, easily serialised etc. and need no special	1193	Strings can easily be printed, easily serialised etc. and need no special
797	procedures to be "valid".	1194	procedures to be "valid".
798		1195
799	And as a result, a miniport consists of a single closure stored in a	1196	And as a result, a port with just a default receiver consists of a single
800	global hash - it can't become much cheaper.	1197	code reference stored in a global hash - it can't become much cheaper.
801		1198
802	=item Why favour JSON, why not a real serialising format such as Storable?	1199	=item Why favour JSON, why not a real serialising format such as Storable?
803		1200
804	In fact, any AnyEvent::MP node will happily accept Storable as framing	1201	In fact, any AnyEvent::MP node will happily accept Storable as framing
805	format, but currently there is no way to make a node use Storable by	1202	format, but currently there is no way to make a node use Storable by
…		…
821		1218
822	L<AnyEvent::MP::Intro> - a gentle introduction.	1219	L<AnyEvent::MP::Intro> - a gentle introduction.
823		1220
824	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1221	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
825		1222
826	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1223	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
827	your applications.	1224	your applications.
		1225
		1226	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1227
		1228	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1229	all nodes.
828		1230
829	L<AnyEvent>.	1231	L<AnyEvent>.
830		1232
831	=head1 AUTHOR	1233	=head1 AUTHOR
832		1234

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC vs. Revision 1.133 by root, Mon Mar 12 10:34:06 2012 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC vs.
Revision 1.133 by root, Mon Mar 12 10:34:06 2012 UTC