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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs.
Revision 1.134 by root, Mon Mar 12 14:47:23 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
43	bin/aemp - stable.	54	bin/aemp - stable.
44	AnyEvent::MP - stable API, should work.	55	AnyEvent::MP - stable API, should work.
45	AnyEvent::MP::Intro - uptodate, but incomplete.	56	AnyEvent::MP::Intro - explains most concepts.
46	AnyEvent::MP::Kernel - mostly stable.	57	AnyEvent::MP::Kernel - mostly stable API.
47	AnyEvent::MP::Global - stable API, protocol not yet final.	58	AnyEvent::MP::Global - stable API.
48
49	stay tuned.
50		59
51	=head1 DESCRIPTION	60	=head1 DESCRIPTION
52		61
53	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
54		63
56	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.
57		66
58	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>
59	manual page and the examples under F<eg/>.	68	manual page and the examples under F<eg/>.
60		69
61	At the moment, this module family is a bit underdocumented.
62
63	=head1 CONCEPTS	70	=head1 CONCEPTS
64		71
65	=over 4	72	=over 4
66		73
67	=item port	74	=item port
68		75
69	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).
70		78
71	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
72	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
73	anything was listening for them or not.	81	anything was listening for them or not.
74		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
75	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
76		86
77	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<#>)
78	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).
79		90
80	=item node	91	=item node
81		92
82	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,
83	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
84	ports.	95	ports.
85		96
86	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
87	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
88	currently.	99	currently, but all nodes can talk to public nodes.
89		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
90	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
91		104
92	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
93	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
94	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
95	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
96		109
97	=item binds - C<ip:port>	110	=item binds - C<ip:port>
98		111
99	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
100	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
101	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
102	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.
103		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
104	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
105		150
106	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
107	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.
108	network. This node is called a seed.
109		153
110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	154	=item global nodes
111	are expected to be long-running, and at least one of those should always
112	be available. When nodes run out of connections (e.g. due to a network
113	error), they try to re-establish connections to some seednodes again to
114	join the network.
115		155
116	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
117	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).
118		170
119	=back	171	=back
120		172
121	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
122		174
…		…
124		176
125	=cut	177	=cut
126		178
127	package AnyEvent::MP;	179	package AnyEvent::MP;
128		180
		181	use AnyEvent::MP::Config ();
129	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
130		184
131	use common::sense;	185	use common::sense;
132		186
133	use Carp ();	187	use Carp ();
134		188
135	use AE ();	189	use AE ();
		190	use Guard ();
136		191
137	use base "Exporter";	192	use base "Exporter";
138		193
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	194	our $VERSION = $AnyEvent::MP::Config::VERSION;
140		195
141	our @EXPORT = qw(	196	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	197	NODE $NODE *SELF node_of after
143	initialise_node	198	configure
144	snd rcv mon mon_guard kil reg psub spawn	199	snd rcv mon mon_guard kil psub peval spawn cal
145	port	200	port
		201	db_set db_del db_reg
		202	db_mon db_family db_keys db_values
146	);	203	);
147		204
148	our $SELF;	205	our $SELF;
149		206
150	sub _self_die() {	207	sub _self_die() {
…		…
155		212
156	=item $thisnode = NODE / $NODE	213	=item $thisnode = NODE / $NODE
157		214
158	The C<NODE> function returns, and the C<$NODE> variable contains, the node	215	The C<NODE> function returns, and the C<$NODE> variable contains, the node
159	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
160	a call to C<initialise_node>.	217	a call to C<configure>.
161		218
162	=item $nodeid = node_of $port	219	=item $nodeid = node_of $port
163		220
164	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.
165		222
166	=item initialise_node $profile_name, key => value...	223	=item configure $profile, key => value...
		224
		225	=item configure key => value...
167		226
168	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
169	"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
170	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
171	some other nodes in the network to discover other nodes.	230	some other nodes in the network to discover other nodes.
172		231
173	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
174	never) before calling other AnyEvent::MP functions.	233	never) before calling other AnyEvent::MP functions.
175		234
176	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
177	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:
178		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
179	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
180	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.
181		270
		271	The profile data is then gathered as follows:
		272
182	First, all remaining key => value pairs (all of which are conviniently	273	First, all remaining key => value pairs (all of which are conveniently
183	undocumented at the moment) will be used. Then they will be overwritten by	274	undocumented at the moment) will be interpreted as configuration
184	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
185	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
186	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
187	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.
188		282
189	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
190	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
191	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
192		294
193	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
194	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
195	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
196	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
197	binds, but it can still talk to all "normal" nodes).	299	binds, but it can still talk to all "normal" nodes).
198		300
199	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
200	used.	302	used, meaning the node will bind on a dynamically-assigned port on every
		303	local IP address it finds.
201		304
		305	=item step 3, connect to seed nodes
		306
202	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
203	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
204	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.
205		310
206	Example: become a distributed node listening on the guessed noderef, or	311	=back
207	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.
208	most common form of invocation for "daemon"-type nodes.	314	This should be the most common form of invocation for "daemon"-type nodes.
209		315
210	initialise_node;	316	configure
211		317
212	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
213	clients.	319	commandline clients.
214		320
215	initialise_node "anon/";	321	configure nodeid => "myscript/%n/%u";
216		322
217	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
218	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,
219	on the resulting addresses.	325	customary for aemp).
220		326
221	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)"
222		338
223	=item $SELF	339	=item $SELF
224		340
225	Contains the current port id while executing C<rcv> callbacks or C<psub>	341	Contains the current port id while executing C<rcv> callbacks or C<psub>
226	blocks.	342	blocks.
…		…
282		398
283	=cut	399	=cut
284		400
285	sub rcv($@);	401	sub rcv($@);
286		402
287	sub _kilme {	403	my $KILME = sub {
288	die "received message on port without callback";	404	(my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g;
289	}	405	kil $SELF, unhandled_message => "missing (tag or fallback) callback for message '$tag'";
		406	};
290		407
291	sub port(;&) {	408	sub port(;&) {
292	my $id = "$UNIQ." . $ID++;	409	my $id = $UNIQ . ++$ID;
293	my $port = "$NODE#$id";	410	my $port = "$NODE#$id";
294		411
295	rcv $port, shift \|\| \&_kilme;	412	rcv $port, shift \|\| $KILME;
296		413
297	$port	414	$port
298	}	415	}
299		416
300	=item rcv $local_port, $callback->(@msg)	417	=item rcv $local_port, $callback->(@msg)
…		…
305		422
306	The global C<$SELF> (exported by this module) contains C<$port> while	423	The global C<$SELF> (exported by this module) contains C<$port> while
307	executing the callback. Runtime errors during callback execution will	424	executing the callback. Runtime errors during callback execution will
308	result in the port being C<kil>ed.	425	result in the port being C<kil>ed.
309		426
310	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
311	C<tag> match.	428	C<tag> match.
312		429
313	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...	430	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
314		431
315	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
…		…
336	msg1 => sub { ... },	453	msg1 => sub { ... },
337	...	454	...
338	;	455	;
339		456
340	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
341	(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.
342		459
343	rcv $port, $otherport => sub {	460	rcv $port, $otherport => sub {
344	my @reply = @_;	461	my @reply = @_;
345		462
346	rcv $SELF, $otherport;	463	rcv $SELF, $otherport;
…		…
348		465
349	=cut	466	=cut
350		467
351	sub rcv($@) {	468	sub rcv($@) {
352	my $port = shift;	469	my $port = shift;
353	my ($noderef, $portid) = split /#/, $port, 2;	470	my ($nodeid, $portid) = split /#/, $port, 2;
354		471
355	$NODE{$noderef} == $NODE{""}	472	$NODE{$nodeid} == $NODE{""}
356	or Carp::croak "$port: rcv can only be called on local ports, caught";	473	or Carp::croak "$port: rcv can only be called on local ports, caught";
357		474
358	while (@_) {	475	while (@_) {
359	if (ref $_[0]) {	476	if (ref $_[0]) {
360	if (my $self = $PORT_DATA{$portid}) {	477	if (my $self = $PORT_DATA{$portid}) {
361	"AnyEvent::MP::Port" eq ref $self	478	"AnyEvent::MP::Port" eq ref $self
362	or Carp::croak "$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";
363		480
364	$self->[2] = shift;	481	$self->[0] = shift;
365	} else {	482	} else {
366	my $cb = shift;	483	my $cb = shift;
367	$PORT{$portid} = sub {	484	$PORT{$portid} = sub {
368	local $SELF = $port;	485	local $SELF = $port;
369	eval { &$cb }; _self_die if $@;	486	eval { &$cb }; _self_die if $@;
370	};	487	};
371	}	488	}
372	} elsif (defined $_[0]) {	489	} elsif (defined $_[0]) {
373	my $self = $PORT_DATA{$portid} \|\|= do {	490	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	491	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375		492
376	$PORT{$portid} = sub {	493	$PORT{$portid} = sub {
377	local $SELF = $port;	494	local $SELF = $port;
378		495
379	if (my $cb = $self->[1]{$_[0]}) {	496	if (my $cb = $self->[1]{$_[0]}) {
…		…
401	}	518	}
402		519
403	$port	520	$port
404	}	521	}
405		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
406	=item $closure = psub { BLOCK }	560	=item $closure = psub { BLOCK }
407		561
408	Remembers C<$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
409	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>
410	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 $SELF, sub {
		567	BLOCK }, @_ } >>.
411		568
412	This is useful when you register callbacks from C<rcv> callbacks:	569	This is useful when you register callbacks from C<rcv> callbacks:
413		570
414	rcv delayed_reply => sub {	571	rcv delayed_reply => sub {
415	my ($delay, @reply) = @_;	572	my ($delay, @reply) = @_;
…		…
451		608
452	Monitor the given port and do something when the port is killed or	609	Monitor the given port and do something when the port is killed or
453	messages to it were lost, and optionally return a guard that can be used	610	messages to it were lost, and optionally return a guard that can be used
454	to stop monitoring again.	611	to stop monitoring again.
455		612
		613	In the first form (callback), the callback is simply called with any
		614	number of C<@reason> elements (no @reason means that the port was deleted
		615	"normally"). Note also that I<< the callback B<must> never die >>, so use
		616	C<eval> if unsure.
		617
		618	In the second form (another port given), the other port (C<$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
456	C<mon> effectively guarantees that, in the absence of hardware failures,	639	C<mon> effectively guarantees that, in the absence of hardware failures,
457	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
458	arrive, or the monitoring action will be invoked after possible message	641	arrive, or the monitoring action will be invoked after possible message
459	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
460	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
461	port). After the monitoring action was invoked, further messages might get	644	port). After the monitoring action was invoked, further messages might get
462	delivered again.	645	delivered again.
463		646
464	Note that monitoring-actions are one-shot: once messages are lost (and a	647	Inter-host-connection timeouts and monitoring depend on the transport
465	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).
466		651
467	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
468	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
469	"normally"). Note also that I<< the callback B<must> never die >>, so use	654	to ensure some maximum latency.
470	C<eval> if unsure.
471
472	In the second form (another port given), the other port (C<$rcvport>)
473	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
474	"normal" kils nothing happens, while under all other conditions, the other
475	port is killed with the same reason.
476
477	The third form (kill self) is the same as the second form, except that
478	C<$rvport> defaults to C<$SELF>.
479
480	In the last form (message), a message of the form C<@msg, @reason> will be
481	C<snd>.
482
483	As a rule of thumb, monitoring requests should always monitor a port from
484	a local port (or callback). The reason is that kill messages might get
485	lost, just like any other message. Another less obvious reason is that
486	even monitoring requests can get lost (for exmaple, when the connection
487	to the other node goes down permanently). When monitoring a port locally
488	these problems do not exist.
489		655
490	Example: call a given callback when C<$port> is killed.	656	Example: call a given callback when C<$port> is killed.
491		657
492	mon $port, sub { warn "port died because of <@_>\n" };	658	mon $port, sub { warn "port died because of <@_>\n" };
493		659
…		…
500	mon $port, $self => "restart";	666	mon $port, $self => "restart";
501		667
502	=cut	668	=cut
503		669
504	sub mon {	670	sub mon {
505	my ($noderef, $port) = split /#/, shift, 2;	671	my ($nodeid, $port) = split /#/, shift, 2;
506		672
507	my $node = $NODE{$noderef} \|\| add_node $noderef;	673	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
508		674
509	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,';
510		676
511	unless (ref $cb) {	677	unless (ref $cb) {
512	if (@_) {	678	if (@_) {
…		…
521	}	687	}
522		688
523	$node->monitor ($port, $cb);	689	$node->monitor ($port, $cb);
524		690
525	defined wantarray	691	defined wantarray
526	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	692	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
527	}	693	}
528		694
529	=item $guard = mon_guard $port, $ref, $ref...	695	=item $guard = mon_guard $port, $ref, $ref...
530		696
531	Monitors the given C<$port> and keeps the passed references. When the port	697	Monitors the given C<$port> and keeps the passed references. When the port
…		…
554		720
555	=item kil $port[, @reason]	721	=item kil $port[, @reason]
556		722
557	Kill the specified port with the given C<@reason>.	723	Kill the specified port with the given C<@reason>.
558		724
559	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" -
560	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
561	"normally").	727	(C<mon $mport, $lport> form) to get killed.
562		728
563	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>
564	C<mon>, see above).	730	form) get killed with the same reason.
565		731
566	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
567	will be reported as reason C<< die => $@ >>.	733	will be reported as reason C<< die => $@ >>.
568		734
569	Transport/communication errors are reported as C<< transport_error =>	735	Transport/communication errors are reported as C<< transport_error =>
570	$message >>.	736	$message >>.
571		737
572	=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: $!";
573		749
574	=item $port = spawn $node, $initfunc[, @initdata]	750	=item $port = spawn $node, $initfunc[, @initdata]
575		751
576	Creates a port on the node C<$node> (which can also be a port ID, in which	752	Creates a port on the node C<$node> (which can also be a port ID, in which
577	case it's the node where that port resides).	753	case it's the node where that port resides).
…		…
588	the package, then the package above the package and so on (e.g.	764	the package, then the package above the package and so on (e.g.
589	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	765	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
590	exists or it runs out of package names.	766	exists or it runs out of package names.
591		767
592	The init function is then called with the newly-created port as context	768	The init function is then called with the newly-created port as context
593	object (C<$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.
594		772
595	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
596	port, and in the remote init function, immediately monitor the passed	774	port, and in the remote init function, immediately monitor the passed
597	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
598	when there is a problem.	776	when there is a problem.
599		777
		778	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		779	caller before C<spawn> returns (by delaying invocation when spawn is
		780	called for the local node).
		781
600	Example: spawn a chat server port on C<$othernode>.	782	Example: spawn a chat server port on C<$othernode>.
601		783
602	# this node, executed from within a port context:	784	# this node, executed from within a port context:
603	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	785	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
604	mon $server;	786	mon $server;
…		…
618		800
619	sub _spawn {	801	sub _spawn {
620	my $port = shift;	802	my $port = shift;
621	my $init = shift;	803	my $init = shift;
622		804
		805	# rcv will create the actual port
623	local $SELF = "$NODE#$port";	806	local $SELF = "$NODE#$port";
624	eval {	807	eval {
625	&{ load_func $init }	808	&{ load_func $init }
626	};	809	};
627	_self_die if $@;	810	_self_die if $@;
628	}	811	}
629		812
630	sub spawn(@) {	813	sub spawn(@) {
631	my ($noderef, undef) = split /#/, shift, 2;	814	my ($nodeid, undef) = split /#/, shift, 2;
632		815
633	my $id = "$RUNIQ." . $ID++;	816	my $id = $RUNIQ . ++$ID;
634		817
635	$_[0] =~ /::/	818	$_[0] =~ /::/
636	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";
637		820
638	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	821	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
639		822
640	"$noderef#$id"	823	"$nodeid#$id"
641	}	824	}
		825
642		826
643	=item after $timeout, @msg	827	=item after $timeout, @msg
644		828
645	=item after $timeout, $callback	829	=item after $timeout, $callback
646		830
…		…
662	? $action[0]()	846	? $action[0]()
663	: snd @action;	847	: snd @action;
664	};	848	};
665	}	849	}
666		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
667	=back	1052	=back
668		1053
669	=head1 AnyEvent::MP vs. Distributed Erlang	1054	=head1 AnyEvent::MP vs. Distributed Erlang
670		1055
671	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
672	== 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
673	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
674	sample:	1059	sample:
675		1060
676	http://www.Erlang.se/doc/programming_rules.shtml	1061	http://www.erlang.se/doc/programming_rules.shtml
677	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
678	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
679	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
680		1065
681	Despite the similarities, there are also some important differences:	1066	Despite the similarities, there are also some important differences:
682		1067
683	=over 4	1068	=over 4
684		1069
685	=item * Node IDs are arbitrary strings in AEMP.	1070	=item * Node IDs are arbitrary strings in AEMP.
686		1071
687	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
688	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
689	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.
690		1076
691	=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
692	uses "local ports are like remote ports".	1078	uses "local ports are like remote ports".
693		1079
694	The failure modes for local ports are quite different (runtime errors	1080	The failure modes for local ports are quite different (runtime errors
…		…
703	ports being the special case/exception, where transport errors cannot	1089	ports being the special case/exception, where transport errors cannot
704	occur.	1090	occur.
705		1091
706	=item * Erlang uses processes and a mailbox, AEMP does not queue.	1092	=item * Erlang uses processes and a mailbox, AEMP does not queue.
707		1093
708	Erlang uses processes that selectively receive messages, and therefore	1094	Erlang uses processes that selectively receive messages out of order, and
709	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
710	useful purpose. For the same reason the pattern-matching abilities of	1096	no useful purpose. For the same reason the pattern-matching abilities
711	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
712	filter messages without dequeing them.	1098	filter messages without dequeuing them.
713		1099
714	(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.
715		1105
716	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	1106	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
717		1107
718	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
719	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
720	connection establishment is handled in the background.	1111	establishment is handled in the background.
721		1112
722	=item * Erlang suffers from silent message loss, AEMP does not.	1113	=item * Erlang suffers from silent message loss, AEMP does not.
723		1114
724	Erlang makes few guarantees on messages delivery - messages can get lost	1115	Erlang implements few guarantees on messages delivery - messages can get
725	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,
726	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).
727		1118
728	AEMP guarantees correct ordering, and the guarantee that after one message	1119	AEMP guarantees (modulo hardware errors) correct ordering, and the
729	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
730	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
731	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.
732		1128
733	=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.
734		1130
735	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
736	known to other nodes for a completely different process, causing messages	1132	process ID known to other nodes for a completely different process,
737	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.
738		1135
739	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
740	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.
741		1138
742	=item * Erlang uses unprotected connections, AEMP uses secure	1139	=item * Erlang uses unprotected connections, AEMP uses secure
743	authentication and can use TLS.	1140	authentication and can use TLS.
744		1141
…		…
747		1144
748	=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
749	communications.	1146	communications.
750		1147
751	The AEMP protocol, unlike the Erlang protocol, supports both programming	1148	The AEMP protocol, unlike the Erlang protocol, supports both programming
752	language independent text-only protocols (good for debugging) and binary,	1149	language independent text-only protocols (good for debugging), and binary,
753	language-specific serialisers (e.g. Storable). By default, unless TLS is	1150	language-specific serialisers (e.g. Storable). By default, unless TLS is
754	used, the protocol is actually completely text-based.	1151	used, the protocol is actually completely text-based.
755		1152
756	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
757	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
758	protocol simple.	1155	protocol simple.
759		1156
760	=item * AEMP has more flexible monitoring options than Erlang.	1157	=item * AEMP has more flexible monitoring options than Erlang.
761		1158
762	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
763	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
764	difficult to implement. Monitoring in AEMP is more flexible than in	1161	difficult to implement.
765	Erlang, as one can choose between automatic kill, exit message or callback	1162
766	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.
767		1165
768	=item * Erlang tries to hide remote/local connections, AEMP does not.	1166	=item * Erlang tries to hide remote/local connections, AEMP does not.
769		1167
770	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
771	same way as linking is (except linking is unreliable in Erlang).	1169	same way as linking is (except linking is unreliable in Erlang).
…		…
793	overhead, as well as having to keep a proxy object everywhere.	1191	overhead, as well as having to keep a proxy object everywhere.
794		1192
795	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
796	procedures to be "valid".	1194	procedures to be "valid".
797		1195
798	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
799	global hash - it can't become much cheaper.	1197	code reference stored in a global hash - it can't become much cheaper.
800		1198
801	=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?
802		1200
803	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
804	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
…		…
820		1218
821	L<AnyEvent::MP::Intro> - a gentle introduction.	1219	L<AnyEvent::MP::Intro> - a gentle introduction.
822		1220
823	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1221	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
824		1222
825	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1223	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
826	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.
827		1230
828	L<AnyEvent>.	1231	L<AnyEvent>.
829		1232
830	=head1 AUTHOR	1233	=head1 AUTHOR
831		1234

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs. Revision 1.134 by root, Mon Mar 12 14:47:23 2012 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs.
Revision 1.134 by root, Mon Mar 12 14:47:23 2012 UTC