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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs.
Revision 1.111 by root, Sat Mar 20 20:12:18 2010 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 prot 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
76	=item port ID - C<noderef#portname>	83	=item port ID - C<nodeid#portname>
77		84
78	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as	85	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	86	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		87
83	=item node	88	=item node
84		89
85	A node is a single process containing at least one port - the node port,	90	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	91	which enables nodes to manage each other remotely, and to create new
87	ports.	92	ports.
88		93
89	Nodes are either private (single-process only), slaves (can only talk to	94	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	95	(no listening ports). Private nodes cannot talk to other private nodes
91	from any other node).	96	currently.
92		97
93	=item node ID - C<[a-za-Z0-9_\-.:]+>	98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
94		99
95	A node ID is a string that uniquely identifies the node within a	100	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	101	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	102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
98	doesn't interpret node IDs in any way.	103	doesn't interpret node IDs in any way.
102	Nodes can only talk to each other by creating some kind of connection to	107	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	108	each other. To do this, nodes should listen on one or more local transport
104	endpoints - binds. Currently, only standard C<ip:port> specifications can	109	endpoints - binds. Currently, only standard C<ip:port> specifications can
105	be used, which specify TCP ports to listen on.	110	be used, which specify TCP ports to listen on.
106		111
107	=item seeds - C<host:port>	112	=item seed nodes
108		113
109	When a node starts, it knows nothing about the network. To teach the node	114	When a node starts, it knows nothing about the network. To teach the node
110	about the network it first has to contact some other node within the	115	about the network it first has to contact some other node within the
111	network. This node is called a seed.	116	network. This node is called a seed.
112		117
113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	118	Apart from the fact that other nodes know them as seed nodes and they have
		119	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		120	any node can function as a seed node for others.
		121
		122	In addition to discovering the network, seed nodes are also used to
		123	maintain the network and to connect nodes that otherwise would have
		124	trouble connecting. They form the backbone of an AnyEvent::MP network.
		125
114	are expected to be long-running, and at least one of those should always	126	Seed nodes are expected to be long-running, and at least one seed node
115	be available. When nodes run out of connections (e.g. due to a network	127	should always be available. They should also be relatively responsive - a
116	error), they try to re-establish connections to some seednodes again to	128	seed node that blocks for long periods will slow down everybody else.
117	join the network.	129
		130	=item seeds - C<host:port>
		131
		132	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		133	TCP port) of nodes that should be used as seed nodes.
		134
		135	The nodes listening on those endpoints are expected to be long-running,
		136	and at least one of those should always be available. When nodes run out
		137	of connections (e.g. due to a network error), they try to re-establish
		138	connections to some seednodes again to join the network.
118		139
119	=back	140	=back
120		141
121	=head1 VARIABLES/FUNCTIONS	142	=head1 VARIABLES/FUNCTIONS
122		143
…		…
134		155
135	use AE ();	156	use AE ();
136		157
137	use base "Exporter";	158	use base "Exporter";
138		159
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	160	our $VERSION = 1.27;
140		161
141	our @EXPORT = qw(	162	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	163	NODE $NODE *SELF node_of after
143	resolve_node initialise_node	164	configure
144	snd rcv mon mon_guard kil reg psub spawn	165	snd rcv mon mon_guard kil psub peval spawn cal
145	port	166	port
146	);	167	);
147		168
148	our $SELF;	169	our $SELF;
149		170
…		…
153	kil $SELF, die => $msg;	174	kil $SELF, die => $msg;
154	}	175	}
155		176
156	=item $thisnode = NODE / $NODE	177	=item $thisnode = NODE / $NODE
157		178
158	The C<NODE> function returns, and the C<$NODE> variable contains the node	179	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	180	ID of the node running in the current process. This value is initialised by
160	a call to C<initialise_node>.	181	a call to C<configure>.
161		182
162	=item $nodeid = node_of $port	183	=item $nodeid = node_of $port
163		184
164	Extracts and returns the node ID part from a port ID or a node ID.	185	Extracts and returns the node ID from a port ID or a node ID.
165		186
166	=item initialise_node $profile_name	187	=item configure $profile, key => value...
		188
		189	=item configure key => value...
167		190
168	Before a node can talk to other nodes on the network (i.e. enter	191	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	192	"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	193	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.	194	some other nodes in the network to discover other nodes.
172		195
		196	The key/value pairs are basically the same ones as documented for the
		197	F<aemp> command line utility (sans the set/del prefix).
		198
173	This function initialises a node - it must be called exactly once (or	199	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	200	never) before calling other AnyEvent::MP functions.
175		201
176	The first argument is a profile name. If it is C<undef> or missing, then	202	=over 4
177	the current nodename will be used instead (i.e. F<uname -n>).
178		203
		204	=item step 1, gathering configuration from profiles
		205
179	The function then looks up the profile in the aemp configuration (see the	206	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility).	207	L<aemp> commandline utility). The profile name can be specified via the
		208	named C<profile> parameter or can simply be the first parameter). If it is
		209	missing, then the nodename (F<uname -n>) will be used as profile name.
		210
		211	The profile data is then gathered as follows:
		212
		213	First, all remaining key => value pairs (all of which are conveniently
		214	undocumented at the moment) will be interpreted as configuration
		215	data. Then they will be overwritten by any values specified in the global
		216	default configuration (see the F<aemp> utility), then the chain of
		217	profiles chosen by the profile name (and any C<parent> attributes).
		218
		219	That means that the values specified in the profile have highest priority
		220	and the values specified directly via C<configure> have lowest priority,
		221	and can only be used to specify defaults.
181		222
182	If the profile specifies a node ID, then this will become the node ID of	223	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	224	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.	225	special node ID of C<anon/> will be replaced by a random node ID.
		226
		227	=item step 2, bind listener sockets
185		228
186	The next step is to look up the binds in the profile, followed by binding	229	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	230	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	231	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	232	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).	233	binds, but it can still talk to all "normal" nodes).
191		234
192	If the profile does not specify a binds list, then the node ID will be	235	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	236	used, meaning the node will bind on a dynamically-assigned port on every
194	used as binds list.	237	local IP address it finds.
195		238
		239	=item step 3, connect to seed nodes
		240
196	Lastly, the seeds list from the profile is passed to the	241	As the last step, the seeds list from the profile is passed to the
197	L<AnyEvent::MP::Global> module, which will then use it to keep	242	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.	243	connectivity with at least one node at any point in time.
199		244
200	Example: become a distributed node listening on the guessed noderef, or	245	=back
201	the one specified via C<aemp> for the current node. This should be the	246
		247	Example: become a distributed node using the local node name as profile.
202	most common form of invocation for "daemon"-type nodes.	248	This should be the most common form of invocation for "daemon"-type nodes.
203		249
204	initialise_node;	250	configure
205		251
206	Example: become an anonymous node. This form is often used for commandline	252	Example: become an anonymous node. This form is often used for commandline
207	clients.	253	clients.
208		254
209	initialise_node "anon/";	255	configure nodeid => "anon/";
210		256
211	Example: become a distributed node. If there is no profile of the given	257	Example: configure a node using a profile called seed, which si suitable
212	name, or no binds list was specified, resolve C<localhost:4044> and bind	258	for a seed node as it binds on all local addresses on a fixed port (4040,
213	on the resulting addresses.	259	customary for aemp).
214		260
215	initialise_node "localhost:4044";	261	# use the aemp commandline utility
		262	# aemp profile seed nodeid anon/ binds '*:4040'
		263
		264	# then use it
		265	configure profile => "seed";
		266
		267	# or simply use aemp from the shell again:
		268	# aemp run profile seed
		269
		270	# or provide a nicer-to-remember nodeid
		271	# aemp run profile seed nodeid "$(hostname)"
216		272
217	=item $SELF	273	=item $SELF
218		274
219	Contains the current port id while executing C<rcv> callbacks or C<psub>	275	Contains the current port id while executing C<rcv> callbacks or C<psub>
220	blocks.	276	blocks.
221		277
222	=item SELF, %SELF, @SELF...	278	=item *SELF, SELF, %SELF, @SELF...
223		279
224	Due to some quirks in how perl exports variables, it is impossible to	280	Due to some quirks in how perl exports variables, it is impossible to
225	just export C<$SELF>, all the symbols called C<SELF> are exported by this	281	just export C<$SELF>, all the symbols named C<SELF> are exported by this
226	module, but only C<$SELF> is currently used.	282	module, but only C<$SELF> is currently used.
227		283
228	=item snd $port, type => @data	284	=item snd $port, type => @data
229		285
230	=item snd $port, @msg	286	=item snd $port, @msg
231		287
232	Send the given message to the given port ID, which can identify either	288	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.	289	local or a remote port, and must be a port ID.
234		290
235	While the message can be about anything, it is highly recommended to use a	291	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	292	use a string as first element (a port ID, or some word that indicates a
237	type etc.).	293	request type etc.) and to consist if only simple perl values (scalars,
		294	arrays, hashes) - if you think you need to pass an object, think again.
238		295
239	The message data effectively becomes read-only after a call to this	296	The message data logically becomes read-only after a call to this
240	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument (or values referenced by them) is
241	problems.	298	forbidden, as there can be considerable time between the call to C<snd>
		299	and the time the message is actually being serialised - in fact, it might
		300	never be copied as within the same process it is simply handed to the
		301	receiving port.
242		302
243	The type of data you can transfer depends on the transport protocol: when	303	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	304	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	305	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	306	that Storable can serialise and deserialise is allowed, and for the local
247	node, anything can be passed.	307	node, anything can be passed. Best rely only on the common denominator of
		308	these.
248		309
249	=item $local_port = port	310	=item $local_port = port
250		311
251	Create a new local port object and returns its port ID. Initially it has	312	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.	313	no callbacks set and will throw an error when it receives messages.
…		…
325	msg1 => sub { ... },	386	msg1 => sub { ... },
326	...	387	...
327	;	388	;
328		389
329	Example: temporarily register a rcv callback for a tag matching some port	390	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.	391	(e.g. for an rpc reply) and unregister it after a message was received.
331		392
332	rcv $port, $otherport => sub {	393	rcv $port, $otherport => sub {
333	my @reply = @_;	394	my @reply = @_;
334		395
335	rcv $SELF, $otherport;	396	rcv $SELF, $otherport;
…		…
337		398
338	=cut	399	=cut
339		400
340	sub rcv($@) {	401	sub rcv($@) {
341	my $port = shift;	402	my $port = shift;
342	my ($noderef, $portid) = split /#/, $port, 2;	403	my ($nodeid, $portid) = split /#/, $port, 2;
343		404
344	$NODE{$noderef} == $NODE{""}	405	$NODE{$nodeid} == $NODE{""}
345	or Carp::croak "$port: rcv can only be called on local ports, caught";	406	or Carp::croak "$port: rcv can only be called on local ports, caught";
346		407
347	while (@_) {	408	while (@_) {
348	if (ref $_[0]) {	409	if (ref $_[0]) {
349	if (my $self = $PORT_DATA{$portid}) {	410	if (my $self = $PORT_DATA{$portid}) {
350	"AnyEvent::MP::Port" eq ref $self	411	"AnyEvent::MP::Port" eq ref $self
351	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	412	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
352		413
353	$self->[2] = shift;	414	$self->[0] = shift;
354	} else {	415	} else {
355	my $cb = shift;	416	my $cb = shift;
356	$PORT{$portid} = sub {	417	$PORT{$portid} = sub {
357	local $SELF = $port;	418	local $SELF = $port;
358	eval { &$cb }; _self_die if $@;	419	eval { &$cb }; _self_die if $@;
359	};	420	};
360	}	421	}
361	} elsif (defined $_[0]) {	422	} elsif (defined $_[0]) {
362	my $self = $PORT_DATA{$portid} \|\|= do {	423	my $self = $PORT_DATA{$portid} \|\|= do {
363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	424	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
364		425
365	$PORT{$portid} = sub {	426	$PORT{$portid} = sub {
366	local $SELF = $port;	427	local $SELF = $port;
367		428
368	if (my $cb = $self->[1]{$_[0]}) {	429	if (my $cb = $self->[1]{$_[0]}) {
…		…
390	}	451	}
391		452
392	$port	453	$port
393	}	454	}
394		455
		456	=item peval $port, $coderef[, @args]
		457
		458	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		459	when the code throews an exception the C<$port> will be killed.
		460
		461	Any remaining args will be passed to the callback. Any return values will
		462	be returned to the caller.
		463
		464	This is useful when you temporarily want to execute code in the context of
		465	a port.
		466
		467	Example: create a port and run some initialisation code in it's context.
		468
		469	my $port = port { ... };
		470
		471	peval $port, sub {
		472	init
		473	or die "unable to init";
		474	};
		475
		476	=cut
		477
		478	sub peval($$) {
		479	local $SELF = shift;
		480	my $cb = shift;
		481
		482	if (wantarray) {
		483	my @res = eval { &$cb };
		484	_self_die if $@;
		485	@res
		486	} else {
		487	my $res = eval { &$cb };
		488	_self_die if $@;
		489	$res
		490	}
		491	}
		492
395	=item $closure = psub { BLOCK }	493	=item $closure = psub { BLOCK }
396		494
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	495	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>	496	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.	497	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		498
		499	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		500	BLOCK } } >>.
400		501
401	This is useful when you register callbacks from C<rcv> callbacks:	502	This is useful when you register callbacks from C<rcv> callbacks:
402		503
403	rcv delayed_reply => sub {	504	rcv delayed_reply => sub {
404	my ($delay, @reply) = @_;	505	my ($delay, @reply) = @_;
…		…
428	$res	529	$res
429	}	530	}
430	}	531	}
431	}	532	}
432		533
433	=item $guard = mon $port, $cb->(@reason)	534	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
434		535
435	=item $guard = mon $port, $rcvport	536	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
436		537
437	=item $guard = mon $port	538	=item $guard = mon $port # kill $SELF when $port dies
438		539
439	=item $guard = mon $port, $rcvport, @msg	540	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
440		541
441	Monitor the given port and do something when the port is killed or	542	Monitor the given port and do something when the port is killed or
442	messages to it were lost, and optionally return a guard that can be used	543	messages to it were lost, and optionally return a guard that can be used
443	to stop monitoring again.	544	to stop monitoring again.
444
445	C<mon> effectively guarantees that, in the absence of hardware failures,
446	that after starting the monitor, either all messages sent to the port
447	will arrive, or the monitoring action will be invoked after possible
448	message loss has been detected. No messages will be lost "in between"
449	(after the first lost message no further messages will be received by the
450	port). After the monitoring action was invoked, further messages might get
451	delivered again.
452
453	Note that monitoring-actions are one-shot: once released, they are removed
454	and will not trigger again.
455		545
456	In the first form (callback), the callback is simply called with any	546	In the first form (callback), the callback is simply called with any
457	number of C<@reason> elements (no @reason means that the port was deleted	547	number of C<@reason> elements (no @reason means that the port was deleted
458	"normally"). Note also that I<< the callback B<must> never die >>, so use	548	"normally"). Note also that I<< the callback B<must> never die >>, so use
459	C<eval> if unsure.	549	C<eval> if unsure.
460		550
461	In the second form (another port given), the other port (C<$rcvport>)	551	In the second form (another port given), the other port (C<$rcvport>)
462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	552	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
463	"normal" kils nothing happens, while under all other conditions, the other	553	"normal" kils nothing happens, while under all other conditions, the other
464	port is killed with the same reason.	554	port is killed with the same reason.
465		555
466	The third form (kill self) is the same as the second form, except that	556	The third form (kill self) is the same as the second form, except that
467	C<$rvport> defaults to C<$SELF>.	557	C<$rvport> defaults to C<$SELF>.
468		558
469	In the last form (message), a message of the form C<@msg, @reason> will be	559	In the last form (message), a message of the form C<@msg, @reason> will be
470	C<snd>.	560	C<snd>.
		561
		562	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		563	alert was raised), they are removed and will not trigger again.
471		564
472	As a rule of thumb, monitoring requests should always monitor a port from	565	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	566	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	567	lost, just like any other message. Another less obvious reason is that
475	even monitoring requests can get lost (for exmaple, when the connection	568	even monitoring requests can get lost (for example, when the connection
476	to the other node goes down permanently). When monitoring a port locally	569	to the other node goes down permanently). When monitoring a port locally
477	these problems do not exist.	570	these problems do not exist.
478		571
		572	C<mon> effectively guarantees that, in the absence of hardware failures,
		573	after starting the monitor, either all messages sent to the port will
		574	arrive, or the monitoring action will be invoked after possible message
		575	loss has been detected. No messages will be lost "in between" (after
		576	the first lost message no further messages will be received by the
		577	port). After the monitoring action was invoked, further messages might get
		578	delivered again.
		579
		580	Inter-host-connection timeouts and monitoring depend on the transport
		581	used. The only transport currently implemented is TCP, and AnyEvent::MP
		582	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		583	non-idle connection, and usually around two hours for idle connections).
		584
		585	This means that monitoring is good for program errors and cleaning up
		586	stuff eventually, but they are no replacement for a timeout when you need
		587	to ensure some maximum latency.
		588
479	Example: call a given callback when C<$port> is killed.	589	Example: call a given callback when C<$port> is killed.
480		590
481	mon $port, sub { warn "port died because of <@_>\n" };	591	mon $port, sub { warn "port died because of <@_>\n" };
482		592
483	Example: kill ourselves when C<$port> is killed abnormally.	593	Example: kill ourselves when C<$port> is killed abnormally.
…		…
489	mon $port, $self => "restart";	599	mon $port, $self => "restart";
490		600
491	=cut	601	=cut
492		602
493	sub mon {	603	sub mon {
494	my ($noderef, $port) = split /#/, shift, 2;	604	my ($nodeid, $port) = split /#/, shift, 2;
495		605
496	my $node = $NODE{$noderef} \|\| add_node $noderef;	606	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
497		607
498	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	608	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
499		609
500	unless (ref $cb) {	610	unless (ref $cb) {
501	if (@_) {	611	if (@_) {
…		…
510	}	620	}
511		621
512	$node->monitor ($port, $cb);	622	$node->monitor ($port, $cb);
513		623
514	defined wantarray	624	defined wantarray
515	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	625	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
516	}	626	}
517		627
518	=item $guard = mon_guard $port, $ref, $ref...	628	=item $guard = mon_guard $port, $ref, $ref...
519		629
520	Monitors the given C<$port> and keeps the passed references. When the port	630	Monitors the given C<$port> and keeps the passed references. When the port
521	is killed, the references will be freed.	631	is killed, the references will be freed.
522		632
523	Optionally returns a guard that will stop the monitoring.	633	Optionally returns a guard that will stop the monitoring.
524		634
525	This function is useful when you create e.g. timers or other watchers and	635	This function is useful when you create e.g. timers or other watchers and
526	want to free them when the port gets killed:	636	want to free them when the port gets killed (note the use of C<psub>):
527		637
528	$port->rcv (start => sub {	638	$port->rcv (start => sub {
529	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	639	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
530	undef $timer if 0.9 < rand;	640	undef $timer if 0.9 < rand;
531	});	641	});
532	});	642	});
533		643
534	=cut	644	=cut
…		…
543		653
544	=item kil $port[, @reason]	654	=item kil $port[, @reason]
545		655
546	Kill the specified port with the given C<@reason>.	656	Kill the specified port with the given C<@reason>.
547		657
548	If no C<@reason> is specified, then the port is killed "normally" (linked	658	If no C<@reason> is specified, then the port is killed "normally" -
549	ports will not be kileld, or even notified).	659	monitor callback will be invoked, but the kil will not cause linked ports
		660	(C<mon $mport, $lport> form) to get killed.
550		661
551	Otherwise, linked ports get killed with the same reason (second form of	662	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
552	C<mon>, see below).	663	form) get killed with the same reason.
553		664
554	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	665	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
555	will be reported as reason C<< die => $@ >>.	666	will be reported as reason C<< die => $@ >>.
556		667
557	Transport/communication errors are reported as C<< transport_error =>	668	Transport/communication errors are reported as C<< transport_error =>
…		…
562	=item $port = spawn $node, $initfunc[, @initdata]	673	=item $port = spawn $node, $initfunc[, @initdata]
563		674
564	Creates a port on the node C<$node> (which can also be a port ID, in which	675	Creates a port on the node C<$node> (which can also be a port ID, in which
565	case it's the node where that port resides).	676	case it's the node where that port resides).
566		677
567	The port ID of the newly created port is return immediately, and it is	678	The port ID of the newly created port is returned immediately, and it is
568	permissible to immediately start sending messages or monitor the port.	679	possible to immediately start sending messages or to monitor the port.
569		680
570	After the port has been created, the init function is	681	After the port has been created, the init function is called on the remote
571	called. This function must be a fully-qualified function name	682	node, in the same context as a C<rcv> callback. This function must be a
572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	683	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
573	program, use C<::name>.	684	specify a function in the main program, use C<::name>.
574		685
575	If the function doesn't exist, then the node tries to C<require>	686	If the function doesn't exist, then the node tries to C<require>
576	the package, then the package above the package and so on (e.g.	687	the package, then the package above the package and so on (e.g.
577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	688	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
578	exists or it runs out of package names.	689	exists or it runs out of package names.
579		690
580	The init function is then called with the newly-created port as context	691	The init function is then called with the newly-created port as context
581	object (C<$SELF>) and the C<@initdata> values as arguments.	692	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		693	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		694	the port might not get created.
582		695
583	A common idiom is to pass your own port, monitor the spawned port, and	696	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	697	port, and in the remote init function, immediately monitor the passed
585	ensures that both ports get cleaned up when there is a problem.	698	local port. This two-way monitoring ensures that both ports get cleaned up
		699	when there is a problem.
		700
		701	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		702	caller before C<spawn> returns (by delaying invocation when spawn is
		703	called for the local node).
586		704
587	Example: spawn a chat server port on C<$othernode>.	705	Example: spawn a chat server port on C<$othernode>.
588		706
589	# this node, executed from within a port context:	707	# this node, executed from within a port context:
590	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	708	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
605		723
606	sub _spawn {	724	sub _spawn {
607	my $port = shift;	725	my $port = shift;
608	my $init = shift;	726	my $init = shift;
609		727
		728	# rcv will create the actual port
610	local $SELF = "$NODE#$port";	729	local $SELF = "$NODE#$port";
611	eval {	730	eval {
612	&{ load_func $init }	731	&{ load_func $init }
613	};	732	};
614	_self_die if $@;	733	_self_die if $@;
615	}	734	}
616		735
617	sub spawn(@) {	736	sub spawn(@) {
618	my ($noderef, undef) = split /#/, shift, 2;	737	my ($nodeid, undef) = split /#/, shift, 2;
619		738
620	my $id = "$RUNIQ." . $ID++;	739	my $id = "$RUNIQ." . $ID++;
621		740
622	$_[0] =~ /::/	741	$_[0] =~ /::/
623	or Carp::croak "spawn init function must be a fully-qualified name, caught";	742	or Carp::croak "spawn init function must be a fully-qualified name, caught";
624		743
625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	744	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
626		745
627	"$noderef#$id"	746	"$nodeid#$id"
628	}	747	}
629		748
630	=item after $timeout, @msg	749	=item after $timeout, @msg
631		750
632	=item after $timeout, $callback	751	=item after $timeout, $callback
633		752
634	Either sends the given message, or call the given callback, after the	753	Either sends the given message, or call the given callback, after the
635	specified number of seconds.	754	specified number of seconds.
636		755
637	This is simply a utility function that come sin handy at times.	756	This is simply a utility function that comes in handy at times - the
		757	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		758	so it may go away in the future.
638		759
639	=cut	760	=cut
640		761
641	sub after($@) {	762	sub after($@) {
642	my ($timeout, @action) = @_;	763	my ($timeout, @action) = @_;
…		…
647	? $action[0]()	768	? $action[0]()
648	: snd @action;	769	: snd @action;
649	};	770	};
650	}	771	}
651		772
		773	=item cal $port, @msg, $callback[, $timeout]
		774
		775	A simple form of RPC - sends a message to the given C<$port> with the
		776	given contents (C<@msg>), but adds a reply port to the message.
		777
		778	The reply port is created temporarily just for the purpose of receiving
		779	the reply, and will be C<kil>ed when no longer needed.
		780
		781	A reply message sent to the port is passed to the C<$callback> as-is.
		782
		783	If an optional time-out (in seconds) is given and it is not C<undef>,
		784	then the callback will be called without any arguments after the time-out
		785	elapsed and the port is C<kil>ed.
		786
		787	If no time-out is given (or it is C<undef>), then the local port will
		788	monitor the remote port instead, so it eventually gets cleaned-up.
		789
		790	Currently this function returns the temporary port, but this "feature"
		791	might go in future versions unless you can make a convincing case that
		792	this is indeed useful for something.
		793
		794	=cut
		795
		796	sub cal(@) {
		797	my $timeout = ref $_[-1] ? undef : pop;
		798	my $cb = pop;
		799
		800	my $port = port {
		801	undef $timeout;
		802	kil $SELF;
		803	&$cb;
		804	};
		805
		806	if (defined $timeout) {
		807	$timeout = AE::timer $timeout, 0, sub {
		808	undef $timeout;
		809	kil $port;
		810	$cb->();
		811	};
		812	} else {
		813	mon $_[0], sub {
		814	kil $port;
		815	$cb->();
		816	};
		817	}
		818
		819	push @_, $port;
		820	&snd;
		821
		822	$port
		823	}
		824
652	=back	825	=back
653		826
654	=head1 AnyEvent::MP vs. Distributed Erlang	827	=head1 AnyEvent::MP vs. Distributed Erlang
655		828
656	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	829	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	830	== 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	831	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
659	sample:	832	sample:
660		833
661	http://www.Erlang.se/doc/programming_rules.shtml	834	http://www.erlang.se/doc/programming_rules.shtml
662	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	835	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	836	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	837	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
665		838
666	Despite the similarities, there are also some important differences:	839	Despite the similarities, there are also some important differences:
667		840
668	=over 4	841	=over 4
669		842
670	=item * Node IDs are arbitrary strings in AEMP.	843	=item * Node IDs are arbitrary strings in AEMP.
671		844
672	Erlang relies on special naming and DNS to work everywhere in the same	845	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	846	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.	847	configuration or DNS), and possibly the addresses of some seed nodes, but
		848	will otherwise discover other nodes (and their IDs) itself.
675		849
676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	850	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
677	uses "local ports are like remote ports".	851	uses "local ports are like remote ports".
678		852
679	The failure modes for local ports are quite different (runtime errors	853	The failure modes for local ports are quite different (runtime errors
…		…
692		866
693	Erlang uses processes that selectively receive messages, and therefore	867	Erlang uses processes that selectively receive messages, and therefore
694	needs a queue. AEMP is event based, queuing messages would serve no	868	needs a queue. AEMP is event based, queuing messages would serve no
695	useful purpose. For the same reason the pattern-matching abilities of	869	useful purpose. For the same reason the pattern-matching abilities of
696	AnyEvent::MP are more limited, as there is little need to be able to	870	AnyEvent::MP are more limited, as there is little need to be able to
697	filter messages without dequeing them.	871	filter messages without dequeuing them.
698		872
699	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	873	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
700		874
701	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	875	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
702		876
…		…
704	so does not need a queue that can overflow). AEMP sends are immediate,	878	so does not need a queue that can overflow). AEMP sends are immediate,
705	connection establishment is handled in the background.	879	connection establishment is handled in the background.
706		880
707	=item * Erlang suffers from silent message loss, AEMP does not.	881	=item * Erlang suffers from silent message loss, AEMP does not.
708		882
709	Erlang makes few guarantees on messages delivery - messages can get lost	883	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,	884	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).	885	b, and c, and the other side only receives messages a and c).
712		886
713	AEMP guarantees correct ordering, and the guarantee that there are no	887	AEMP guarantees correct ordering, and the guarantee that after one message
714	holes in the message sequence.	888	is lost, all following ones sent to the same port are lost as well, until
715		889	monitoring raises an error, so there are no silent "holes" in the message
716	=item * In Erlang, processes can be declared dead and later be found to be	890	sequence.
717	alive.
718
719	In Erlang it can happen that a monitored process is declared dead and
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		891
727	=item * Erlang can send messages to the wrong port, AEMP does not.	892	=item * Erlang can send messages to the wrong port, AEMP does not.
728		893
729	In Erlang it is quite likely that a node that restarts reuses a process ID	894	In Erlang it is quite likely that a node that restarts reuses a process ID
730	known to other nodes for a completely different process, causing messages	895	known to other nodes for a completely different process, causing messages
…		…
734	around in the network will not be sent to an unrelated port.	899	around in the network will not be sent to an unrelated port.
735		900
736	=item * Erlang uses unprotected connections, AEMP uses secure	901	=item * Erlang uses unprotected connections, AEMP uses secure
737	authentication and can use TLS.	902	authentication and can use TLS.
738		903
739	AEMP can use a proven protocol - SSL/TLS - to protect connections and	904	AEMP can use a proven protocol - TLS - to protect connections and
740	securely authenticate nodes.	905	securely authenticate nodes.
741		906
742	=item * The AEMP protocol is optimised for both text-based and binary	907	=item * The AEMP protocol is optimised for both text-based and binary
743	communications.	908	communications.
744		909
745	The AEMP protocol, unlike the Erlang protocol, supports both	910	The AEMP protocol, unlike the Erlang protocol, supports both programming
746	language-independent text-only protocols (good for debugging) and binary,	911	language independent text-only protocols (good for debugging) and binary,
747	language-specific serialisers (e.g. Storable).	912	language-specific serialisers (e.g. Storable). By default, unless TLS is
		913	used, the protocol is actually completely text-based.
748		914
749	It has also been carefully designed to be implementable in other languages	915	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	916	with a minimum of work while gracefully degrading functionality to make the
751	protocol simple.	917	protocol simple.
752		918
753	=item * AEMP has more flexible monitoring options than Erlang.	919	=item * AEMP has more flexible monitoring options than Erlang.
754		920
755	In Erlang, you can chose to receive I<all> exit signals as messages	921	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
758	Erlang, as one can choose between automatic kill, exit message or callback	924	Erlang, as one can choose between automatic kill, exit message or callback
759	on a per-process basis.	925	on a per-process basis.
760		926
761	=item * Erlang tries to hide remote/local connections, AEMP does not.	927	=item * Erlang tries to hide remote/local connections, AEMP does not.
762		928
763	Monitoring in Erlang is not an indicator of process death/crashes,	929	Monitoring in Erlang is not an indicator of process death/crashes, in the
764	as linking is (except linking is unreliable in Erlang).	930	same way as linking is (except linking is unreliable in Erlang).
765		931
766	In AEMP, you don't "look up" registered port names or send to named ports	932	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	933	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	934	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	935	remote port. Since both monitors are local to the node, they are much more
770	more reliable.	936	reliable (no need for C<spawn_link>).
771		937
772	This also saves round-trips and avoids sending messages to the wrong port	938	This also saves round-trips and avoids sending messages to the wrong port
773	(hard to do in Erlang).	939	(hard to do in Erlang).
774		940
775	=back	941	=back
776		942
777	=head1 RATIONALE	943	=head1 RATIONALE
778		944
779	=over 4	945	=over 4
780		946
781	=item Why strings for ports and noderefs, why not objects?	947	=item Why strings for port and node IDs, why not objects?
782		948
783	We considered "objects", but found that the actual number of methods	949	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	950	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	951	the network frequently, the serialising/deserialising would add lots of
786	overhead, as well as having to keep a proxy object.	952	overhead, as well as having to keep a proxy object everywhere.
787		953
788	Strings can easily be printed, easily serialised etc. and need no special	954	Strings can easily be printed, easily serialised etc. and need no special
789	procedures to be "valid".	955	procedures to be "valid".
790		956
791	And a a miniport consists of a single closure stored in a global hash - it	957	And as a result, a port with just a default receiver consists of a single
792	can't become much cheaper.	958	closure stored in a global hash - it can't become much cheaper.
793		959
794	=item Why favour JSON, why not real serialising format such as Storable?	960	=item Why favour JSON, why not a real serialising format such as Storable?
795		961
796	In fact, any AnyEvent::MP node will happily accept Storable as framing	962	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	963	format, but currently there is no way to make a node use Storable by
798	default.	964	default (although all nodes will accept it).
799		965
800	The default framing protocol is JSON because a) JSON::XS is many times	966	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	967	faster for small messages and b) most importantly, after years of
802	experience we found that object serialisation is causing more problems	968	experience we found that object serialisation is causing more problems
803	than it gains: Just like function calls, objects simply do not travel	969	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	970	easily over the network, mostly because they will always be a copy, so you
805	always have to re-think your design.	971	always have to re-think your design.
806		972
807	Keeping your messages simple, concentrating on data structures rather than	973	Keeping your messages simple, concentrating on data structures rather than
808	objects, will keep your messages clean, tidy and efficient.	974	objects, will keep your messages clean, tidy and efficient.
809		975
810	=back	976	=back
811		977
812	=head1 SEE ALSO	978	=head1 SEE ALSO
813		979
		980	L<AnyEvent::MP::Intro> - a gentle introduction.
		981
		982	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		983
		984	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		985	your applications.
		986
		987	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		988
		989	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		990	all nodes.
		991
814	L<AnyEvent>.	992	L<AnyEvent>.
815		993
816	=head1 AUTHOR	994	=head1 AUTHOR
817		995
818	Marc Lehmann <schmorp@schmorp.de>	996	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs. Revision 1.111 by root, Sat Mar 20 20:12:18 2010 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs.
Revision 1.111 by root, Sat Mar 20 20:12:18 2010 UTC