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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs.
Revision 1.121 by root, Tue Feb 28 18:37:24 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 $localport, $cb->(@msg) # callback is invoked on death
38	mon $port, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
39	mon $port, $otherport, @msg # send message on death	42	mon $localport, $otherport, @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 - WIP
46	AnyEvent::MP::Transport - mostly stable	57	AnyEvent::MP::Kernel - mostly stable API.
47		58	AnyEvent::MP::Global - stable API.
48	stay tuned.
49		59
50	=head1 DESCRIPTION	60	=head1 DESCRIPTION
51		61
52	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
53		63
54	Despite its simplicity, you can securely message other processes running	64	Despite its simplicity, you can securely message other processes running
55	on the same or other hosts.	65	on the same or other hosts, and you can supervise entities remotely.
56		66
57	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>
58	manual page.	68	manual page and the examples under F<eg/>.
59
60	At the moment, this module family is severly broken and underdocumented,
61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
62	stay tuned!
63		69
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<noderef#portname>	85	=item port ID - C<nodeid#portname>
77		86
78	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
79	separator, and a port name (a printable string of unspecified format). An	88	separator, and a port name (a printable string of unspecified format).
80	exception is the the node port, whose ID is identical to its node
81	reference.
82		89
83	=item node	90	=item node
84		91
85	A node is a single process containing at least one port - the node port,	92	A node is a single process containing at least one port - the node port,
86	which provides nodes to manage each other remotely, and to create new	93	which enables nodes to manage each other remotely, and to create new
87	ports.	94	ports.
88		95
89	Nodes are either private (single-process only), slaves (can only talk to	96	Nodes are either public (have one or more listening ports) or private
90	public nodes, but do not need an open port) or public nodes (connectable	97	(no listening ports). Private nodes cannot talk to other private nodes
91	from any other node).	98	currently, but all nodes can talk to public nodes.
92		99
		100	Nodes is represented by (printable) strings called "node IDs".
		101
93	=item node ID - C<[a-za-Z0-9_\-.:]+>	102	=item node ID - C<[A-Za-z0-9_\-.:]*>
94		103
95	A node ID is a string that uniquely identifies the node within a	104	A node ID is a string that uniquely identifies the node within a
96	network. Depending on the configuration used, node IDs can look like a	105	network. Depending on the configuration used, node IDs can look like a
97	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	106	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
98	doesn't interpret node IDs in any way.	107	doesn't interpret node IDs in any way except to uniquely identify a node.
99		108
100	=item binds - C<ip:port>	109	=item binds - C<ip:port>
101		110
102	Nodes can only talk to each other by creating some kind of connection to	111	Nodes can only talk to each other by creating some kind of connection to
103	each other. To do this, nodes should listen on one or more local transport	112	each other. To do this, nodes should listen on one or more local transport
		113	endpoints - binds.
		114
104	endpoints - binds. Currently, only standard C<ip:port> specifications can	115	Currently, only standard C<ip:port> specifications can be used, which
105	be used, which specify TCP ports to listen on.	116	specify TCP ports to listen on. So a bind is basically just a tcp socket
		117	in listening mode thta accepts conenctions form other nodes.
106		118
		119	=item seed nodes
		120
		121	When a node starts, it knows nothing about the network it is in - it
		122	needs to connect to at least one other node that is already in the
		123	network. These other nodes are called "seed nodes".
		124
		125	Seed nodes themselves are not special - they are seed nodes only because
		126	some other node I<uses> them as such, but any node can be used as seed
		127	node for other nodes, and eahc node cna use a different set of seed nodes.
		128
		129	In addition to discovering the network, seed nodes are also used to
		130	maintain the network - all nodes using the same seed node form are part of
		131	the same network. If a network is split into multiple subnets because e.g.
		132	the network link between the parts goes down, then using the same seed
		133	nodes for all nodes ensures that eventually the subnets get merged again.
		134
		135	Seed nodes are expected to be long-running, and at least one seed node
		136	should always be available. They should also be relatively responsive - a
		137	seed node that blocks for long periods will slow down everybody else.
		138
		139	For small networks, it's best if every node uses the same set of seed
		140	nodes. For large networks, it can be useful to specify "regional" seed
		141	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		142	each other. What's important is that all seed nodes connections form a
		143	complete graph, so that the network cannot split into separate subnets
		144	forever.
		145
		146	Seed nodes are represented by seed IDs.
		147
107	=item seeds - C<host:port>	148	=item seed IDs - C<host:port>
108		149
109	When a node starts, it knows nothing about the network. To teach the node	150	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
110	about the network it first has to contact some other node within the	151	TCP port) of nodes that should be used as seed nodes.
111	network. This node is called a seed.
112		152
113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	153	=item global nodes
114	are expected to be long-running, and at least one of those should always	154
115	be available. When nodes run out of connections (e.g. due to a network	155	An AEMP network needs a discovery service - nodes need to know how to
116	error), they try to re-establish connections to some seednodes again to	156	connect to other nodes they only know by name. In addition, AEMP offers a
117	join the network.	157	distributed "group database", which maps group names to a list of strings
		158	- for example, to register worker ports.
		159
		160	A network needs at least one global node to work, and allows every node to
		161	be a global node.
		162
		163	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		164	node and tries to keep connections to all other nodes. So while it can
		165	make sense to make every node "global" in small networks, it usually makes
		166	sense to only make seed nodes into global nodes in large networks (nodes
		167	keep connections to seed nodes and global nodes, so makign them the same
		168	reduces overhead).
118		169
119	=back	170	=back
120		171
121	=head1 VARIABLES/FUNCTIONS	172	=head1 VARIABLES/FUNCTIONS
122		173
124		175
125	=cut	176	=cut
126		177
127	package AnyEvent::MP;	178	package AnyEvent::MP;
128		179
		180	use AnyEvent::MP::Config ();
129	use AnyEvent::MP::Kernel;	181	use AnyEvent::MP::Kernel;
		182	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
130		183
131	use common::sense;	184	use common::sense;
132		185
133	use Carp ();	186	use Carp ();
134		187
135	use AE ();	188	use AE ();
136		189
137	use base "Exporter";	190	use base "Exporter";
138		191
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	192	our $VERSION = $AnyEvent::MP::Config::VERSION;
140		193
141	our @EXPORT = qw(	194	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	195	NODE $NODE *SELF node_of after
143	resolve_node initialise_node	196	configure
144	snd rcv mon mon_guard kil reg psub spawn	197	snd rcv mon mon_guard kil psub peval spawn cal
145	port	198	port
146	);	199	);
147		200
148	our $SELF;	201	our $SELF;
149		202
…		…
153	kil $SELF, die => $msg;	206	kil $SELF, die => $msg;
154	}	207	}
155		208
156	=item $thisnode = NODE / $NODE	209	=item $thisnode = NODE / $NODE
157		210
158	The C<NODE> function returns, and the C<$NODE> variable contains the node	211	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	212	ID of the node running in the current process. This value is initialised by
160	a call to C<initialise_node>.	213	a call to C<configure>.
161		214
162	=item $nodeid = node_of $port	215	=item $nodeid = node_of $port
163		216
164	Extracts and returns the node ID part from a port ID or a node ID.	217	Extracts and returns the node ID from a port ID or a node ID.
165		218
166	=item initialise_node $profile_name	219	=item configure $profile, key => value...
		220
		221	=item configure key => value...
167		222
168	Before a node can talk to other nodes on the network (i.e. enter	223	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	224	"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	225	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.	226	some other nodes in the network to discover other nodes.
172		227
173	This function initialises a node - it must be called exactly once (or	228	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	229	never) before calling other AnyEvent::MP functions.
175		230
176	The first argument is a profile name. If it is C<undef> or missing, then	231	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>).	232	F<aemp> command line utility (sans the set/del prefix), with two additions:
178		233
		234	=over 4
		235
		236	=item norc => $boolean (default false)
		237
		238	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		239	be consulted - all configuraiton options must be specified in the
		240	C<configure> call.
		241
		242	=item force => $boolean (default false)
		243
		244	IF true, then the values specified in the C<configure> will take
		245	precedence over any values configured via the rc file. The default is for
		246	the rc file to override any options specified in the program.
		247
		248	=back
		249
		250	=over 4
		251
		252	=item step 1, gathering configuration from profiles
		253
179	The function then looks up the profile in the aemp configuration (see the	254	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility).	255	L<aemp> commandline utility). The profile name can be specified via the
		256	named C<profile> parameter or can simply be the first parameter). If it is
		257	missing, then the nodename (F<uname -n>) will be used as profile name.
		258
		259	The profile data is then gathered as follows:
		260
		261	First, all remaining key => value pairs (all of which are conveniently
		262	undocumented at the moment) will be interpreted as configuration
		263	data. Then they will be overwritten by any values specified in the global
		264	default configuration (see the F<aemp> utility), then the chain of
		265	profiles chosen by the profile name (and any C<parent> attributes).
		266
		267	That means that the values specified in the profile have highest priority
		268	and the values specified directly via C<configure> have lowest priority,
		269	and can only be used to specify defaults.
181		270
182	If the profile specifies a node ID, then this will become the node ID of	271	If the profile specifies a node ID, then this will become the node ID of
183	this process. If not, then the profile name will be used as node ID. The	272	this process. If not, then the profile name will be used as node ID. The
184	special node ID of C<anon/> will be replaced by a random node ID.	273	special node ID of C<anon/> will be replaced by a random node ID.
		274
		275	=item step 2, bind listener sockets
185		276
186	The next step is to look up the binds in the profile, followed by binding	277	The next step is to look up the binds in the profile, followed by binding
187	aemp protocol listeners on all binds specified (it is possible and valid	278	aemp protocol listeners on all binds specified (it is possible and valid
188	to have no binds, meaning that the node cannot be contacted form the	279	to have no binds, meaning that the node cannot be contacted form the
189	outside. This means the node cannot talk to other nodes that also have no	280	outside. This means the node cannot talk to other nodes that also have no
190	binds, but it can still talk to all "normal" nodes).	281	binds, but it can still talk to all "normal" nodes).
191		282
192	If the profile does not specify a binds list, then the node ID will be	283	If the profile does not specify a binds list, then a default of C<*> is
193	treated as if it were of the form C<host:port>, which will be resolved and	284	used, meaning the node will bind on a dynamically-assigned port on every
194	used as binds list.	285	local IP address it finds.
195		286
		287	=item step 3, connect to seed nodes
		288
196	Lastly, the seeds list from the profile is passed to the	289	As the last step, the seed ID list from the profile is passed to the
197	L<AnyEvent::MP::Global> module, which will then use it to keep	290	L<AnyEvent::MP::Global> module, which will then use it to keep
198	connectivity with at least on of those seed nodes at any point in time.	291	connectivity with at least one node at any point in time.
199		292
200	Example: become a distributed node listening on the guessed noderef, or	293	=back
201	the one specified via C<aemp> for the current node. This should be the	294
		295	Example: become a distributed node using the local node name as profile.
202	most common form of invocation for "daemon"-type nodes.	296	This should be the most common form of invocation for "daemon"-type nodes.
203		297
204	initialise_node;	298	configure
205		299
206	Example: become an anonymous node. This form is often used for commandline	300	Example: become an anonymous node. This form is often used for commandline
207	clients.	301	clients.
208		302
209	initialise_node "anon/";	303	configure nodeid => "anon/";
210		304
211	Example: become a distributed node. If there is no profile of the given	305	Example: configure a node using a profile called seed, which is suitable
212	name, or no binds list was specified, resolve C<localhost:4044> and bind	306	for a seed node as it binds on all local addresses on a fixed port (4040,
213	on the resulting addresses.	307	customary for aemp).
214		308
215	initialise_node "localhost:4044";	309	# use the aemp commandline utility
		310	# aemp profile seed nodeid anon/ binds '*:4040'
		311
		312	# then use it
		313	configure profile => "seed";
		314
		315	# or simply use aemp from the shell again:
		316	# aemp run profile seed
		317
		318	# or provide a nicer-to-remember nodeid
		319	# aemp run profile seed nodeid "$(hostname)"
216		320
217	=item $SELF	321	=item $SELF
218		322
219	Contains the current port id while executing C<rcv> callbacks or C<psub>	323	Contains the current port id while executing C<rcv> callbacks or C<psub>
220	blocks.	324	blocks.
221		325
222	=item SELF, %SELF, @SELF...	326	=item *SELF, SELF, %SELF, @SELF...
223		327
224	Due to some quirks in how perl exports variables, it is impossible to	328	Due to some quirks in how perl exports variables, it is impossible to
225	just export C<$SELF>, all the symbols called C<SELF> are exported by this	329	just export C<$SELF>, all the symbols named C<SELF> are exported by this
226	module, but only C<$SELF> is currently used.	330	module, but only C<$SELF> is currently used.
227		331
228	=item snd $port, type => @data	332	=item snd $port, type => @data
229		333
230	=item snd $port, @msg	334	=item snd $port, @msg
231		335
232	Send the given message to the given port ID, which can identify either	336	Send the given message to the given port, which can identify either a
233	a local or a remote port, and must be a port ID.	337	local or a remote port, and must be a port ID.
234		338
235	While the message can be about anything, it is highly recommended to use a	339	While the message can be almost anything, it is highly recommended to
236	string as first element (a port ID, or some word that indicates a request	340	use a string as first element (a port ID, or some word that indicates a
237	type etc.).	341	request type etc.) and to consist if only simple perl values (scalars,
		342	arrays, hashes) - if you think you need to pass an object, think again.
238		343
239	The message data effectively becomes read-only after a call to this	344	The message data logically becomes read-only after a call to this
240	function: modifying any argument is not allowed and can cause many	345	function: modifying any argument (or values referenced by them) is
241	problems.	346	forbidden, as there can be considerable time between the call to C<snd>
		347	and the time the message is actually being serialised - in fact, it might
		348	never be copied as within the same process it is simply handed to the
		349	receiving port.
242		350
243	The type of data you can transfer depends on the transport protocol: when	351	The type of data you can transfer depends on the transport protocol: when
244	JSON is used, then only strings, numbers and arrays and hashes consisting	352	JSON is used, then only strings, numbers and arrays and hashes consisting
245	of those are allowed (no objects). When Storable is used, then anything	353	of those are allowed (no objects). When Storable is used, then anything
246	that Storable can serialise and deserialise is allowed, and for the local	354	that Storable can serialise and deserialise is allowed, and for the local
247	node, anything can be passed.	355	node, anything can be passed. Best rely only on the common denominator of
		356	these.
248		357
249	=item $local_port = port	358	=item $local_port = port
250		359
251	Create a new local port object and returns its port ID. Initially it has	360	Create a new local port object and returns its port ID. Initially it has
252	no callbacks set and will throw an error when it receives messages.	361	no callbacks set and will throw an error when it receives messages.
…		…
276	sub _kilme {	385	sub _kilme {
277	die "received message on port without callback";	386	die "received message on port without callback";
278	}	387	}
279		388
280	sub port(;&) {	389	sub port(;&) {
281	my $id = "$UNIQ." . $ID++;	390	my $id = "$UNIQ." . ++$ID;
282	my $port = "$NODE#$id";	391	my $port = "$NODE#$id";
283		392
284	rcv $port, shift \|\| \&_kilme;	393	rcv $port, shift \|\| \&_kilme;
285		394
286	$port	395	$port
…		…
325	msg1 => sub { ... },	434	msg1 => sub { ... },
326	...	435	...
327	;	436	;
328		437
329	Example: temporarily register a rcv callback for a tag matching some port	438	Example: temporarily register a rcv callback for a tag matching some port
330	(e.g. for a rpc reply) and unregister it after a message was received.	439	(e.g. for an rpc reply) and unregister it after a message was received.
331		440
332	rcv $port, $otherport => sub {	441	rcv $port, $otherport => sub {
333	my @reply = @_;	442	my @reply = @_;
334		443
335	rcv $SELF, $otherport;	444	rcv $SELF, $otherport;
…		…
337		446
338	=cut	447	=cut
339		448
340	sub rcv($@) {	449	sub rcv($@) {
341	my $port = shift;	450	my $port = shift;
342	my ($noderef, $portid) = split /#/, $port, 2;	451	my ($nodeid, $portid) = split /#/, $port, 2;
343		452
344	$NODE{$noderef} == $NODE{""}	453	$NODE{$nodeid} == $NODE{""}
345	or Carp::croak "$port: rcv can only be called on local ports, caught";	454	or Carp::croak "$port: rcv can only be called on local ports, caught";
346		455
347	while (@_) {	456	while (@_) {
348	if (ref $_[0]) {	457	if (ref $_[0]) {
349	if (my $self = $PORT_DATA{$portid}) {	458	if (my $self = $PORT_DATA{$portid}) {
350	"AnyEvent::MP::Port" eq ref $self	459	"AnyEvent::MP::Port" eq ref $self
351	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	460	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
352		461
353	$self->[2] = shift;	462	$self->[0] = shift;
354	} else {	463	} else {
355	my $cb = shift;	464	my $cb = shift;
356	$PORT{$portid} = sub {	465	$PORT{$portid} = sub {
357	local $SELF = $port;	466	local $SELF = $port;
358	eval { &$cb }; _self_die if $@;	467	eval { &$cb }; _self_die if $@;
359	};	468	};
360	}	469	}
361	} elsif (defined $_[0]) {	470	} elsif (defined $_[0]) {
362	my $self = $PORT_DATA{$portid} \|\|= do {	471	my $self = $PORT_DATA{$portid} \|\|= do {
363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	472	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
364		473
365	$PORT{$portid} = sub {	474	$PORT{$portid} = sub {
366	local $SELF = $port;	475	local $SELF = $port;
367		476
368	if (my $cb = $self->[1]{$_[0]}) {	477	if (my $cb = $self->[1]{$_[0]}) {
…		…
390	}	499	}
391		500
392	$port	501	$port
393	}	502	}
394		503
		504	=item peval $port, $coderef[, @args]
		505
		506	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		507	when the code throews an exception the C<$port> will be killed.
		508
		509	Any remaining args will be passed to the callback. Any return values will
		510	be returned to the caller.
		511
		512	This is useful when you temporarily want to execute code in the context of
		513	a port.
		514
		515	Example: create a port and run some initialisation code in it's context.
		516
		517	my $port = port { ... };
		518
		519	peval $port, sub {
		520	init
		521	or die "unable to init";
		522	};
		523
		524	=cut
		525
		526	sub peval($$) {
		527	local $SELF = shift;
		528	my $cb = shift;
		529
		530	if (wantarray) {
		531	my @res = eval { &$cb };
		532	_self_die if $@;
		533	@res
		534	} else {
		535	my $res = eval { &$cb };
		536	_self_die if $@;
		537	$res
		538	}
		539	}
		540
395	=item $closure = psub { BLOCK }	541	=item $closure = psub { BLOCK }
396		542
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	543	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
398	closure is executed, sets up the environment in the same way as in C<rcv>	544	closure is executed, sets up the environment in the same way as in C<rcv>
399	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	545	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		546
		547	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		548	BLOCK }, @_ } >>.
400		549
401	This is useful when you register callbacks from C<rcv> callbacks:	550	This is useful when you register callbacks from C<rcv> callbacks:
402		551
403	rcv delayed_reply => sub {	552	rcv delayed_reply => sub {
404	my ($delay, @reply) = @_;	553	my ($delay, @reply) = @_;
…		…
428	$res	577	$res
429	}	578	}
430	}	579	}
431	}	580	}
432		581
433	=item $guard = mon $port, $cb->(@reason)	582	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
434		583
435	=item $guard = mon $port, $rcvport	584	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
436		585
437	=item $guard = mon $port	586	=item $guard = mon $port # kill $SELF when $port dies
438		587
439	=item $guard = mon $port, $rcvport, @msg	588	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
440		589
441	Monitor the given port and do something when the port is killed or	590	Monitor the given port and do something when the port is killed or
442	messages to it were lost, and optionally return a guard that can be used	591	messages to it were lost, and optionally return a guard that can be used
443	to stop monitoring again.	592	to stop monitoring again.
444
445	C<mon> effectively guarantees that, in the absence of hardware failures,
446	that after starting the monitor, either all messages sent to the port
447	will arrive, or the monitoring action will be invoked after possible
448	message loss has been detected. No messages will be lost "in between"
449	(after the first lost message no further messages will be received by the
450	port). After the monitoring action was invoked, further messages might get
451	delivered again.
452
453	Note that monitoring-actions are one-shot: once released, they are removed
454	and will not trigger again.
455		593
456	In the first form (callback), the callback is simply called with any	594	In the first form (callback), the callback is simply called with any
457	number of C<@reason> elements (no @reason means that the port was deleted	595	number of C<@reason> elements (no @reason means that the port was deleted
458	"normally"). Note also that I<< the callback B<must> never die >>, so use	596	"normally"). Note also that I<< the callback B<must> never die >>, so use
459	C<eval> if unsure.	597	C<eval> if unsure.
460		598
461	In the second form (another port given), the other port (C<$rcvport>)	599	In the second form (another port given), the other port (C<$rcvport>)
462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	600	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
463	"normal" kils nothing happens, while under all other conditions, the other	601	"normal" kils nothing happens, while under all other conditions, the other
464	port is killed with the same reason.	602	port is killed with the same reason.
465		603
466	The third form (kill self) is the same as the second form, except that	604	The third form (kill self) is the same as the second form, except that
467	C<$rvport> defaults to C<$SELF>.	605	C<$rvport> defaults to C<$SELF>.
468		606
469	In the last form (message), a message of the form C<@msg, @reason> will be	607	In the last form (message), a message of the form C<@msg, @reason> will be
470	C<snd>.	608	C<snd>.
		609
		610	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		611	alert was raised), they are removed and will not trigger again.
471		612
472	As a rule of thumb, monitoring requests should always monitor a port from	613	As a rule of thumb, monitoring requests should always monitor a port from
473	a local port (or callback). The reason is that kill messages might get	614	a local port (or callback). The reason is that kill messages might get
474	lost, just like any other message. Another less obvious reason is that	615	lost, just like any other message. Another less obvious reason is that
475	even monitoring requests can get lost (for exmaple, when the connection	616	even monitoring requests can get lost (for example, when the connection
476	to the other node goes down permanently). When monitoring a port locally	617	to the other node goes down permanently). When monitoring a port locally
477	these problems do not exist.	618	these problems do not exist.
478		619
		620	C<mon> effectively guarantees that, in the absence of hardware failures,
		621	after starting the monitor, either all messages sent to the port will
		622	arrive, or the monitoring action will be invoked after possible message
		623	loss has been detected. No messages will be lost "in between" (after
		624	the first lost message no further messages will be received by the
		625	port). After the monitoring action was invoked, further messages might get
		626	delivered again.
		627
		628	Inter-host-connection timeouts and monitoring depend on the transport
		629	used. The only transport currently implemented is TCP, and AnyEvent::MP
		630	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		631	non-idle connection, and usually around two hours for idle connections).
		632
		633	This means that monitoring is good for program errors and cleaning up
		634	stuff eventually, but they are no replacement for a timeout when you need
		635	to ensure some maximum latency.
		636
479	Example: call a given callback when C<$port> is killed.	637	Example: call a given callback when C<$port> is killed.
480		638
481	mon $port, sub { warn "port died because of <@_>\n" };	639	mon $port, sub { warn "port died because of <@_>\n" };
482		640
483	Example: kill ourselves when C<$port> is killed abnormally.	641	Example: kill ourselves when C<$port> is killed abnormally.
…		…
489	mon $port, $self => "restart";	647	mon $port, $self => "restart";
490		648
491	=cut	649	=cut
492		650
493	sub mon {	651	sub mon {
494	my ($noderef, $port) = split /#/, shift, 2;	652	my ($nodeid, $port) = split /#/, shift, 2;
495		653
496	my $node = $NODE{$noderef} \|\| add_node $noderef;	654	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
497		655
498	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	656	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
499		657
500	unless (ref $cb) {	658	unless (ref $cb) {
501	if (@_) {	659	if (@_) {
…		…
510	}	668	}
511		669
512	$node->monitor ($port, $cb);	670	$node->monitor ($port, $cb);
513		671
514	defined wantarray	672	defined wantarray
515	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	673	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
516	}	674	}
517		675
518	=item $guard = mon_guard $port, $ref, $ref...	676	=item $guard = mon_guard $port, $ref, $ref...
519		677
520	Monitors the given C<$port> and keeps the passed references. When the port	678	Monitors the given C<$port> and keeps the passed references. When the port
521	is killed, the references will be freed.	679	is killed, the references will be freed.
522		680
523	Optionally returns a guard that will stop the monitoring.	681	Optionally returns a guard that will stop the monitoring.
524		682
525	This function is useful when you create e.g. timers or other watchers and	683	This function is useful when you create e.g. timers or other watchers and
526	want to free them when the port gets killed:	684	want to free them when the port gets killed (note the use of C<psub>):
527		685
528	$port->rcv (start => sub {	686	$port->rcv (start => sub {
529	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	687	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
530	undef $timer if 0.9 < rand;	688	undef $timer if 0.9 < rand;
531	});	689	});
532	});	690	});
533		691
534	=cut	692	=cut
…		…
543		701
544	=item kil $port[, @reason]	702	=item kil $port[, @reason]
545		703
546	Kill the specified port with the given C<@reason>.	704	Kill the specified port with the given C<@reason>.
547		705
548	If no C<@reason> is specified, then the port is killed "normally" (linked	706	If no C<@reason> is specified, then the port is killed "normally" -
549	ports will not be kileld, or even notified).	707	monitor callback will be invoked, but the kil will not cause linked ports
		708	(C<mon $mport, $lport> form) to get killed.
550		709
551	Otherwise, linked ports get killed with the same reason (second form of	710	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
552	C<mon>, see below).	711	form) get killed with the same reason.
553		712
554	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	713	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
555	will be reported as reason C<< die => $@ >>.	714	will be reported as reason C<< die => $@ >>.
556		715
557	Transport/communication errors are reported as C<< transport_error =>	716	Transport/communication errors are reported as C<< transport_error =>
…		…
562	=item $port = spawn $node, $initfunc[, @initdata]	721	=item $port = spawn $node, $initfunc[, @initdata]
563		722
564	Creates a port on the node C<$node> (which can also be a port ID, in which	723	Creates a port on the node C<$node> (which can also be a port ID, in which
565	case it's the node where that port resides).	724	case it's the node where that port resides).
566		725
567	The port ID of the newly created port is return immediately, and it is	726	The port ID of the newly created port is returned immediately, and it is
568	permissible to immediately start sending messages or monitor the port.	727	possible to immediately start sending messages or to monitor the port.
569		728
570	After the port has been created, the init function is	729	After the port has been created, the init function is called on the remote
571	called. This function must be a fully-qualified function name	730	node, in the same context as a C<rcv> callback. This function must be a
572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	731	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
573	program, use C<::name>.	732	specify a function in the main program, use C<::name>.
574		733
575	If the function doesn't exist, then the node tries to C<require>	734	If the function doesn't exist, then the node tries to C<require>
576	the package, then the package above the package and so on (e.g.	735	the package, then the package above the package and so on (e.g.
577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	736	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
578	exists or it runs out of package names.	737	exists or it runs out of package names.
579		738
580	The init function is then called with the newly-created port as context	739	The init function is then called with the newly-created port as context
581	object (C<$SELF>) and the C<@initdata> values as arguments.	740	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		741	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		742	the port might not get created.
582		743
583	A common idiom is to pass your own port, monitor the spawned port, and	744	A common idiom is to pass a local port, immediately monitor the spawned
584	in the init function, monitor the original port. This two-way monitoring	745	port, and in the remote init function, immediately monitor the passed
585	ensures that both ports get cleaned up when there is a problem.	746	local port. This two-way monitoring ensures that both ports get cleaned up
		747	when there is a problem.
		748
		749	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		750	caller before C<spawn> returns (by delaying invocation when spawn is
		751	called for the local node).
586		752
587	Example: spawn a chat server port on C<$othernode>.	753	Example: spawn a chat server port on C<$othernode>.
588		754
589	# this node, executed from within a port context:	755	# this node, executed from within a port context:
590	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	756	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
605		771
606	sub _spawn {	772	sub _spawn {
607	my $port = shift;	773	my $port = shift;
608	my $init = shift;	774	my $init = shift;
609		775
		776	# rcv will create the actual port
610	local $SELF = "$NODE#$port";	777	local $SELF = "$NODE#$port";
611	eval {	778	eval {
612	&{ load_func $init }	779	&{ load_func $init }
613	};	780	};
614	_self_die if $@;	781	_self_die if $@;
615	}	782	}
616		783
617	sub spawn(@) {	784	sub spawn(@) {
618	my ($noderef, undef) = split /#/, shift, 2;	785	my ($nodeid, undef) = split /#/, shift, 2;
619		786
620	my $id = "$RUNIQ." . $ID++;	787	my $id = "$RUNIQ." . ++$ID;
621		788
622	$_[0] =~ /::/	789	$_[0] =~ /::/
623	or Carp::croak "spawn init function must be a fully-qualified name, caught";	790	or Carp::croak "spawn init function must be a fully-qualified name, caught";
624		791
625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	792	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
626		793
627	"$noderef#$id"	794	"$nodeid#$id"
628	}	795	}
		796
629		797
630	=item after $timeout, @msg	798	=item after $timeout, @msg
631		799
632	=item after $timeout, $callback	800	=item after $timeout, $callback
633		801
634	Either sends the given message, or call the given callback, after the	802	Either sends the given message, or call the given callback, after the
635	specified number of seconds.	803	specified number of seconds.
636		804
637	This is simply a utility function that come sin handy at times.	805	This is simply a utility function that comes in handy at times - the
		806	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		807	so it may go away in the future.
638		808
639	=cut	809	=cut
640		810
641	sub after($@) {	811	sub after($@) {
642	my ($timeout, @action) = @_;	812	my ($timeout, @action) = @_;
…		…
647	? $action[0]()	817	? $action[0]()
648	: snd @action;	818	: snd @action;
649	};	819	};
650	}	820	}
651		821
		822	=item cal $port, @msg, $callback[, $timeout]
		823
		824	A simple form of RPC - sends a message to the given C<$port> with the
		825	given contents (C<@msg>), but adds a reply port to the message.
		826
		827	The reply port is created temporarily just for the purpose of receiving
		828	the reply, and will be C<kil>ed when no longer needed.
		829
		830	A reply message sent to the port is passed to the C<$callback> as-is.
		831
		832	If an optional time-out (in seconds) is given and it is not C<undef>,
		833	then the callback will be called without any arguments after the time-out
		834	elapsed and the port is C<kil>ed.
		835
		836	If no time-out is given (or it is C<undef>), then the local port will
		837	monitor the remote port instead, so it eventually gets cleaned-up.
		838
		839	Currently this function returns the temporary port, but this "feature"
		840	might go in future versions unless you can make a convincing case that
		841	this is indeed useful for something.
		842
		843	=cut
		844
		845	sub cal(@) {
		846	my $timeout = ref $_[-1] ? undef : pop;
		847	my $cb = pop;
		848
		849	my $port = port {
		850	undef $timeout;
		851	kil $SELF;
		852	&$cb;
		853	};
		854
		855	if (defined $timeout) {
		856	$timeout = AE::timer $timeout, 0, sub {
		857	undef $timeout;
		858	kil $port;
		859	$cb->();
		860	};
		861	} else {
		862	mon $_[0], sub {
		863	kil $port;
		864	$cb->();
		865	};
		866	}
		867
		868	push @_, $port;
		869	&snd;
		870
		871	$port
		872	}
		873
652	=back	874	=back
653		875
654	=head1 AnyEvent::MP vs. Distributed Erlang	876	=head1 AnyEvent::MP vs. Distributed Erlang
655		877
656	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	878	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
657	== aemp node, Erlang process == aemp port), so many of the documents and	879	== aemp node, Erlang process == aemp port), so many of the documents and
658	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	880	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
659	sample:	881	sample:
660		882
661	http://www.Erlang.se/doc/programming_rules.shtml	883	http://www.erlang.se/doc/programming_rules.shtml
662	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	884	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
663	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	885	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
664	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	886	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
665		887
666	Despite the similarities, there are also some important differences:	888	Despite the similarities, there are also some important differences:
667		889
668	=over 4	890	=over 4
669		891
670	=item * Node IDs are arbitrary strings in AEMP.	892	=item * Node IDs are arbitrary strings in AEMP.
671		893
672	Erlang relies on special naming and DNS to work everywhere in the same	894	Erlang relies on special naming and DNS to work everywhere in the same
673	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	895	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
674	configuraiton or DNS), but will otherwise discover other odes itself.	896	configuration or DNS), and possibly the addresses of some seed nodes, but
		897	will otherwise discover other nodes (and their IDs) itself.
675		898
676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	899	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
677	uses "local ports are like remote ports".	900	uses "local ports are like remote ports".
678		901
679	The failure modes for local ports are quite different (runtime errors	902	The failure modes for local ports are quite different (runtime errors
…		…
688	ports being the special case/exception, where transport errors cannot	911	ports being the special case/exception, where transport errors cannot
689	occur.	912	occur.
690		913
691	=item * Erlang uses processes and a mailbox, AEMP does not queue.	914	=item * Erlang uses processes and a mailbox, AEMP does not queue.
692		915
693	Erlang uses processes that selectively receive messages, and therefore	916	Erlang uses processes that selectively receive messages out of order, and
694	needs a queue. AEMP is event based, queuing messages would serve no	917	therefore needs a queue. AEMP is event based, queuing messages would serve
695	useful purpose. For the same reason the pattern-matching abilities of	918	no useful purpose. For the same reason the pattern-matching abilities
696	AnyEvent::MP are more limited, as there is little need to be able to	919	of AnyEvent::MP are more limited, as there is little need to be able to
697	filter messages without dequeing them.	920	filter messages without dequeuing them.
698		921
699	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	922	This is not a philosophical difference, but simply stems from AnyEvent::MP
		923	being event-based, while Erlang is process-based.
		924
		925	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		926	top of AEMP and Coro threads.
700		927
701	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	928	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
702		929
703	Sending messages in Erlang is synchronous and blocks the process (and	930	Sending messages in Erlang is synchronous and blocks the process until
		931	a conenction has been established and the message sent (and so does not
704	so does not need a queue that can overflow). AEMP sends are immediate,	932	need a queue that can overflow). AEMP sends return immediately, connection
705	connection establishment is handled in the background.	933	establishment is handled in the background.
706		934
707	=item * Erlang suffers from silent message loss, AEMP does not.	935	=item * Erlang suffers from silent message loss, AEMP does not.
708		936
709	Erlang makes few guarantees on messages delivery - messages can get lost	937	Erlang implements few guarantees on messages delivery - messages can get
710	without any of the processes realising it (i.e. you send messages a, b,	938	lost without any of the processes realising it (i.e. you send messages a,
711	and c, and the other side only receives messages a and c).	939	b, and c, and the other side only receives messages a and c).
712		940
713	AEMP guarantees correct ordering, and the guarantee that there are no	941	AEMP guarantees (modulo hardware errors) correct ordering, and the
		942	guarantee that after one message is lost, all following ones sent to the
		943	same port are lost as well, until monitoring raises an error, so there are
714	holes in the message sequence.	944	no silent "holes" in the message sequence.
715		945
716	=item * In Erlang, processes can be declared dead and later be found to be	946	If you want your software to be very reliable, you have to cope with
717	alive.	947	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
718		948	simply tries to work better in common error cases, such as when a network
719	In Erlang it can happen that a monitored process is declared dead and	949	link goes down.
720	linked processes get killed, but later it turns out that the process is
721	still alive - and can receive messages.
722
723	In AEMP, when port monitoring detects a port as dead, then that port will
724	eventually be killed - it cannot happen that a node detects a port as dead
725	and then later sends messages to it, finding it is still alive.
726		950
727	=item * Erlang can send messages to the wrong port, AEMP does not.	951	=item * Erlang can send messages to the wrong port, AEMP does not.
728		952
729	In Erlang it is quite likely that a node that restarts reuses a process ID	953	In Erlang it is quite likely that a node that restarts reuses an Erlang
730	known to other nodes for a completely different process, causing messages	954	process ID known to other nodes for a completely different process,
731	destined for that process to end up in an unrelated process.	955	causing messages destined for that process to end up in an unrelated
		956	process.
732		957
733	AEMP never reuses port IDs, so old messages or old port IDs floating	958	AEMP does not reuse port IDs, so old messages or old port IDs floating
734	around in the network will not be sent to an unrelated port.	959	around in the network will not be sent to an unrelated port.
735		960
736	=item * Erlang uses unprotected connections, AEMP uses secure	961	=item * Erlang uses unprotected connections, AEMP uses secure
737	authentication and can use TLS.	962	authentication and can use TLS.
738		963
739	AEMP can use a proven protocol - SSL/TLS - to protect connections and	964	AEMP can use a proven protocol - TLS - to protect connections and
740	securely authenticate nodes.	965	securely authenticate nodes.
741		966
742	=item * The AEMP protocol is optimised for both text-based and binary	967	=item * The AEMP protocol is optimised for both text-based and binary
743	communications.	968	communications.
744		969
745	The AEMP protocol, unlike the Erlang protocol, supports both	970	The AEMP protocol, unlike the Erlang protocol, supports both programming
746	language-independent text-only protocols (good for debugging) and binary,	971	language independent text-only protocols (good for debugging), and binary,
747	language-specific serialisers (e.g. Storable).	972	language-specific serialisers (e.g. Storable). By default, unless TLS is
		973	used, the protocol is actually completely text-based.
748		974
749	It has also been carefully designed to be implementable in other languages	975	It has also been carefully designed to be implementable in other languages
750	with a minimum of work while gracefully degrading fucntionality to make the	976	with a minimum of work while gracefully degrading functionality to make the
751	protocol simple.	977	protocol simple.
752		978
753	=item * AEMP has more flexible monitoring options than Erlang.	979	=item * AEMP has more flexible monitoring options than Erlang.
754		980
755	In Erlang, you can chose to receive I<all> exit signals as messages	981	In Erlang, you can chose to receive I<all> exit signals as messages or
756	or I<none>, there is no in-between, so monitoring single processes is	982	I<none>, there is no in-between, so monitoring single Erlang processes is
757	difficult to implement. Monitoring in AEMP is more flexible than in	983	difficult to implement.
758	Erlang, as one can choose between automatic kill, exit message or callback	984
759	on a per-process basis.	985	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		986	between automatic kill, exit message or callback on a per-port basis.
760		987
761	=item * Erlang tries to hide remote/local connections, AEMP does not.	988	=item * Erlang tries to hide remote/local connections, AEMP does not.
762		989
763	Monitoring in Erlang is not an indicator of process death/crashes,	990	Monitoring in Erlang is not an indicator of process death/crashes, in the
764	as linking is (except linking is unreliable in Erlang).	991	same way as linking is (except linking is unreliable in Erlang).
765		992
766	In AEMP, you don't "look up" registered port names or send to named ports	993	In AEMP, you don't "look up" registered port names or send to named ports
767	that might or might not be persistent. Instead, you normally spawn a port	994	that might or might not be persistent. Instead, you normally spawn a port
768	on the remote node. The init function monitors the you, and you monitor	995	on the remote node. The init function monitors you, and you monitor the
769	the remote port. Since both monitors are local to the node, they are much	996	remote port. Since both monitors are local to the node, they are much more
770	more reliable.	997	reliable (no need for C<spawn_link>).
771		998
772	This also saves round-trips and avoids sending messages to the wrong port	999	This also saves round-trips and avoids sending messages to the wrong port
773	(hard to do in Erlang).	1000	(hard to do in Erlang).
774		1001
775	=back	1002	=back
776		1003
777	=head1 RATIONALE	1004	=head1 RATIONALE
778		1005
779	=over 4	1006	=over 4
780		1007
781	=item Why strings for ports and noderefs, why not objects?	1008	=item Why strings for port and node IDs, why not objects?
782		1009
783	We considered "objects", but found that the actual number of methods	1010	We considered "objects", but found that the actual number of methods
784	thatc an be called are very low. Since port IDs and noderefs travel over	1011	that can be called are quite low. Since port and node IDs travel over
785	the network frequently, the serialising/deserialising would add lots of	1012	the network frequently, the serialising/deserialising would add lots of
786	overhead, as well as having to keep a proxy object.	1013	overhead, as well as having to keep a proxy object everywhere.
787		1014
788	Strings can easily be printed, easily serialised etc. and need no special	1015	Strings can easily be printed, easily serialised etc. and need no special
789	procedures to be "valid".	1016	procedures to be "valid".
790		1017
791	And a a miniport consists of a single closure stored in a global hash - it	1018	And as a result, a port with just a default receiver consists of a single
792	can't become much cheaper.	1019	code reference stored in a global hash - it can't become much cheaper.
793		1020
794	=item Why favour JSON, why not real serialising format such as Storable?	1021	=item Why favour JSON, why not a real serialising format such as Storable?
795		1022
796	In fact, any AnyEvent::MP node will happily accept Storable as framing	1023	In fact, any AnyEvent::MP node will happily accept Storable as framing
797	format, but currently there is no way to make a node use Storable by	1024	format, but currently there is no way to make a node use Storable by
798	default.	1025	default (although all nodes will accept it).
799		1026
800	The default framing protocol is JSON because a) JSON::XS is many times	1027	The default framing protocol is JSON because a) JSON::XS is many times
801	faster for small messages and b) most importantly, after years of	1028	faster for small messages and b) most importantly, after years of
802	experience we found that object serialisation is causing more problems	1029	experience we found that object serialisation is causing more problems
803	than it gains: Just like function calls, objects simply do not travel	1030	than it solves: Just like function calls, objects simply do not travel
804	easily over the network, mostly because they will always be a copy, so you	1031	easily over the network, mostly because they will always be a copy, so you
805	always have to re-think your design.	1032	always have to re-think your design.
806		1033
807	Keeping your messages simple, concentrating on data structures rather than	1034	Keeping your messages simple, concentrating on data structures rather than
808	objects, will keep your messages clean, tidy and efficient.	1035	objects, will keep your messages clean, tidy and efficient.
809		1036
810	=back	1037	=back
811		1038
812	=head1 SEE ALSO	1039	=head1 SEE ALSO
813		1040
		1041	L<AnyEvent::MP::Intro> - a gentle introduction.
		1042
		1043	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		1044
		1045	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
		1046	your applications.
		1047
		1048	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1049
		1050	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1051	all nodes.
		1052
814	L<AnyEvent>.	1053	L<AnyEvent>.
815		1054
816	=head1 AUTHOR	1055	=head1 AUTHOR
817		1056
818	Marc Lehmann <schmorp@schmorp.de>	1057	Marc Lehmann <schmorp@schmorp.de>

Diff Legend

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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs. Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC

Diff Legend

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs.
Revision 1.121 by root, Tue Feb 28 18:37:24 2012 UTC