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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC vs.
Revision 1.103 by root, Sat Oct 17 01:42:39 2009 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 = 1.22;
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
173	This function initialises a node - it must be called exactly once (or	196	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	197	never) before calling other AnyEvent::MP functions.
175		198
176	The first argument is a profile name. If it is C<undef> or missing, then	199	=over 4
177	the current nodename will be used instead (i.e. F<uname -n>).
178		200
		201	=item step 1, gathering configuration from profiles
		202
179	The function then looks up the profile in the aemp configuration (see the	203	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility).	204	L<aemp> commandline utility). The profile name can be specified via the
		205	named C<profile> parameter or can simply be the first parameter). If it is
		206	missing, then the nodename (F<uname -n>) will be used as profile name.
		207
		208	The profile data is then gathered as follows:
		209
		210	First, all remaining key => value pairs (all of which are conveniently
		211	undocumented at the moment) will be interpreted as configuration
		212	data. Then they will be overwritten by any values specified in the global
		213	default configuration (see the F<aemp> utility), then the chain of
		214	profiles chosen by the profile name (and any C<parent> attributes).
		215
		216	That means that the values specified in the profile have highest priority
		217	and the values specified directly via C<configure> have lowest priority,
		218	and can only be used to specify defaults.
181		219
182	If the profile specifies a node ID, then this will become the node ID of	220	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	221	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.	222	special node ID of C<anon/> will be replaced by a random node ID.
		223
		224	=item step 2, bind listener sockets
185		225
186	The next step is to look up the binds in the profile, followed by binding	226	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	227	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	228	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	229	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).	230	binds, but it can still talk to all "normal" nodes).
191		231
192	If the profile does not specify a binds list, then the node ID will be	232	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	233	used, meaning the node will bind on a dynamically-assigned port on every
194	used as binds list.	234	local IP address it finds.
195		235
		236	=item step 3, connect to seed nodes
		237
196	Lastly, the seeds list from the profile is passed to the	238	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	239	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.	240	connectivity with at least one node at any point in time.
199		241
200	Example: become a distributed node listening on the guessed noderef, or	242	=back
201	the one specified via C<aemp> for the current node. This should be the	243
		244	Example: become a distributed node using the local node name as profile.
202	most common form of invocation for "daemon"-type nodes.	245	This should be the most common form of invocation for "daemon"-type nodes.
203		246
204	initialise_node;	247	configure
205		248
206	Example: become an anonymous node. This form is often used for commandline	249	Example: become an anonymous node. This form is often used for commandline
207	clients.	250	clients.
208		251
209	initialise_node "anon/";	252	configure nodeid => "anon/";
210		253
211	Example: become a distributed node. If there is no profile of the given	254	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	255	for a seed node as it binds on all local addresses on a fixed port (4040,
213	on the resulting addresses.	256	customary for aemp).
214		257
215	initialise_node "localhost:4044";	258	# use the aemp commandline utility
		259	# aemp profile seed nodeid anon/ binds '*:4040'
		260
		261	# then use it
		262	configure profile => "seed";
		263
		264	# or simply use aemp from the shell again:
		265	# aemp run profile seed
		266
		267	# or provide a nicer-to-remember nodeid
		268	# aemp run profile seed nodeid "$(hostname)"
216		269
217	=item $SELF	270	=item $SELF
218		271
219	Contains the current port id while executing C<rcv> callbacks or C<psub>	272	Contains the current port id while executing C<rcv> callbacks or C<psub>
220	blocks.	273	blocks.
221		274
222	=item SELF, %SELF, @SELF...	275	=item *SELF, SELF, %SELF, @SELF...
223		276
224	Due to some quirks in how perl exports variables, it is impossible to	277	Due to some quirks in how perl exports variables, it is impossible to
225	just export C<$SELF>, all the symbols called C<SELF> are exported by this	278	just export C<$SELF>, all the symbols named C<SELF> are exported by this
226	module, but only C<$SELF> is currently used.	279	module, but only C<$SELF> is currently used.
227		280
228	=item snd $port, type => @data	281	=item snd $port, type => @data
229		282
230	=item snd $port, @msg	283	=item snd $port, @msg
231		284
232	Send the given message to the given port ID, which can identify either	285	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.	286	local or a remote port, and must be a port ID.
234		287
235	While the message can be about anything, it is highly recommended to use a	288	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	289	use a string as first element (a port ID, or some word that indicates a
237	type etc.).	290	request type etc.) and to consist if only simple perl values (scalars,
		291	arrays, hashes) - if you think you need to pass an object, think again.
238		292
239	The message data effectively becomes read-only after a call to this	293	The message data logically becomes read-only after a call to this
240	function: modifying any argument is not allowed and can cause many	294	function: modifying any argument (or values referenced by them) is
241	problems.	295	forbidden, as there can be considerable time between the call to C<snd>
		296	and the time the message is actually being serialised - in fact, it might
		297	never be copied as within the same process it is simply handed to the
		298	receiving port.
242		299
243	The type of data you can transfer depends on the transport protocol: when	300	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	301	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	302	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	303	that Storable can serialise and deserialise is allowed, and for the local
247	node, anything can be passed.	304	node, anything can be passed. Best rely only on the common denominator of
		305	these.
248		306
249	=item $local_port = port	307	=item $local_port = port
250		308
251	Create a new local port object and returns its port ID. Initially it has	309	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.	310	no callbacks set and will throw an error when it receives messages.
…		…
325	msg1 => sub { ... },	383	msg1 => sub { ... },
326	...	384	...
327	;	385	;
328		386
329	Example: temporarily register a rcv callback for a tag matching some port	387	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.	388	(e.g. for an rpc reply) and unregister it after a message was received.
331		389
332	rcv $port, $otherport => sub {	390	rcv $port, $otherport => sub {
333	my @reply = @_;	391	my @reply = @_;
334		392
335	rcv $SELF, $otherport;	393	rcv $SELF, $otherport;
…		…
337		395
338	=cut	396	=cut
339		397
340	sub rcv($@) {	398	sub rcv($@) {
341	my $port = shift;	399	my $port = shift;
342	my ($noderef, $portid) = split /#/, $port, 2;	400	my ($nodeid, $portid) = split /#/, $port, 2;
343		401
344	$NODE{$noderef} == $NODE{""}	402	$NODE{$nodeid} == $NODE{""}
345	or Carp::croak "$port: rcv can only be called on local ports, caught";	403	or Carp::croak "$port: rcv can only be called on local ports, caught";
346		404
347	while (@_) {	405	while (@_) {
348	if (ref $_[0]) {	406	if (ref $_[0]) {
349	if (my $self = $PORT_DATA{$portid}) {	407	if (my $self = $PORT_DATA{$portid}) {
350	"AnyEvent::MP::Port" eq ref $self	408	"AnyEvent::MP::Port" eq ref $self
351	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	409	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
352		410
353	$self->[2] = shift;	411	$self->[0] = shift;
354	} else {	412	} else {
355	my $cb = shift;	413	my $cb = shift;
356	$PORT{$portid} = sub {	414	$PORT{$portid} = sub {
357	local $SELF = $port;	415	local $SELF = $port;
358	eval { &$cb }; _self_die if $@;	416	eval { &$cb }; _self_die if $@;
359	};	417	};
360	}	418	}
361	} elsif (defined $_[0]) {	419	} elsif (defined $_[0]) {
362	my $self = $PORT_DATA{$portid} \|\|= do {	420	my $self = $PORT_DATA{$portid} \|\|= do {
363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	421	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
364		422
365	$PORT{$portid} = sub {	423	$PORT{$portid} = sub {
366	local $SELF = $port;	424	local $SELF = $port;
367		425
368	if (my $cb = $self->[1]{$_[0]}) {	426	if (my $cb = $self->[1]{$_[0]}) {
…		…
390	}	448	}
391		449
392	$port	450	$port
393	}	451	}
394		452
		453	=item peval $port, $coderef[, @args]
		454
		455	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		456	when the code throews an exception the C<$port> will be killed.
		457
		458	Any remaining args will be passed to the callback. Any return values will
		459	be returned to the caller.
		460
		461	This is useful when you temporarily want to execute code in the context of
		462	a port.
		463
		464	Example: create a port and run some initialisation code in it's context.
		465
		466	my $port = port { ... };
		467
		468	peval $port, sub {
		469	init
		470	or die "unable to init";
		471	};
		472
		473	=cut
		474
		475	sub peval($$) {
		476	local $SELF = shift;
		477	my $cb = shift;
		478
		479	if (wantarray) {
		480	my @res = eval { &$cb };
		481	_self_die if $@;
		482	@res
		483	} else {
		484	my $res = eval { &$cb };
		485	_self_die if $@;
		486	$res
		487	}
		488	}
		489
395	=item $closure = psub { BLOCK }	490	=item $closure = psub { BLOCK }
396		491
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	492	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>	493	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.	494	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		495
		496	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		497	BLOCK } } >>.
400		498
401	This is useful when you register callbacks from C<rcv> callbacks:	499	This is useful when you register callbacks from C<rcv> callbacks:
402		500
403	rcv delayed_reply => sub {	501	rcv delayed_reply => sub {
404	my ($delay, @reply) = @_;	502	my ($delay, @reply) = @_;
…		…
428	$res	526	$res
429	}	527	}
430	}	528	}
431	}	529	}
432		530
433	=item $guard = mon $port, $cb->(@reason)	531	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
434		532
435	=item $guard = mon $port, $rcvport	533	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
436		534
437	=item $guard = mon $port	535	=item $guard = mon $port # kill $SELF when $port dies
438		536
439	=item $guard = mon $port, $rcvport, @msg	537	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
440		538
441	Monitor the given port and do something when the port is killed or	539	Monitor the given port and do something when the port is killed or
442	messages to it were lost, and optionally return a guard that can be used	540	messages to it were lost, and optionally return a guard that can be used
443	to stop monitoring again.	541	to stop monitoring again.
444
445	C<mon> effectively guarantees that, in the absence of hardware failures,
446	that after starting the monitor, either all messages sent to the port
447	will arrive, or the monitoring action will be invoked after possible
448	message loss has been detected. No messages will be lost "in between"
449	(after the first lost message no further messages will be received by the
450	port). After the monitoring action was invoked, further messages might get
451	delivered again.
452
453	Note that monitoring-actions are one-shot: once released, they are removed
454	and will not trigger again.
455		542
456	In the first form (callback), the callback is simply called with any	543	In the first form (callback), the callback is simply called with any
457	number of C<@reason> elements (no @reason means that the port was deleted	544	number of C<@reason> elements (no @reason means that the port was deleted
458	"normally"). Note also that I<< the callback B<must> never die >>, so use	545	"normally"). Note also that I<< the callback B<must> never die >>, so use
459	C<eval> if unsure.	546	C<eval> if unsure.
460		547
461	In the second form (another port given), the other port (C<$rcvport>)	548	In the second form (another port given), the other port (C<$rcvport>)
462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	549	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
463	"normal" kils nothing happens, while under all other conditions, the other	550	"normal" kils nothing happens, while under all other conditions, the other
464	port is killed with the same reason.	551	port is killed with the same reason.
465		552
466	The third form (kill self) is the same as the second form, except that	553	The third form (kill self) is the same as the second form, except that
467	C<$rvport> defaults to C<$SELF>.	554	C<$rvport> defaults to C<$SELF>.
468		555
469	In the last form (message), a message of the form C<@msg, @reason> will be	556	In the last form (message), a message of the form C<@msg, @reason> will be
470	C<snd>.	557	C<snd>.
		558
		559	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		560	alert was raised), they are removed and will not trigger again.
471		561
472	As a rule of thumb, monitoring requests should always monitor a port from	562	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	563	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	564	lost, just like any other message. Another less obvious reason is that
475	even monitoring requests can get lost (for exmaple, when the connection	565	even monitoring requests can get lost (for example, when the connection
476	to the other node goes down permanently). When monitoring a port locally	566	to the other node goes down permanently). When monitoring a port locally
477	these problems do not exist.	567	these problems do not exist.
478		568
		569	C<mon> effectively guarantees that, in the absence of hardware failures,
		570	after starting the monitor, either all messages sent to the port will
		571	arrive, or the monitoring action will be invoked after possible message
		572	loss has been detected. No messages will be lost "in between" (after
		573	the first lost message no further messages will be received by the
		574	port). After the monitoring action was invoked, further messages might get
		575	delivered again.
		576
		577	Inter-host-connection timeouts and monitoring depend on the transport
		578	used. The only transport currently implemented is TCP, and AnyEvent::MP
		579	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		580	non-idle connection, and usually around two hours for idle connections).
		581
		582	This means that monitoring is good for program errors and cleaning up
		583	stuff eventually, but they are no replacement for a timeout when you need
		584	to ensure some maximum latency.
		585
479	Example: call a given callback when C<$port> is killed.	586	Example: call a given callback when C<$port> is killed.
480		587
481	mon $port, sub { warn "port died because of <@_>\n" };	588	mon $port, sub { warn "port died because of <@_>\n" };
482		589
483	Example: kill ourselves when C<$port> is killed abnormally.	590	Example: kill ourselves when C<$port> is killed abnormally.
…		…
489	mon $port, $self => "restart";	596	mon $port, $self => "restart";
490		597
491	=cut	598	=cut
492		599
493	sub mon {	600	sub mon {
494	my ($noderef, $port) = split /#/, shift, 2;	601	my ($nodeid, $port) = split /#/, shift, 2;
495		602
496	my $node = $NODE{$noderef} \|\| add_node $noderef;	603	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
497		604
498	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	605	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
499		606
500	unless (ref $cb) {	607	unless (ref $cb) {
501	if (@_) {	608	if (@_) {
…		…
510	}	617	}
511		618
512	$node->monitor ($port, $cb);	619	$node->monitor ($port, $cb);
513		620
514	defined wantarray	621	defined wantarray
515	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	622	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
516	}	623	}
517		624
518	=item $guard = mon_guard $port, $ref, $ref...	625	=item $guard = mon_guard $port, $ref, $ref...
519		626
520	Monitors the given C<$port> and keeps the passed references. When the port	627	Monitors the given C<$port> and keeps the passed references. When the port
521	is killed, the references will be freed.	628	is killed, the references will be freed.
522		629
523	Optionally returns a guard that will stop the monitoring.	630	Optionally returns a guard that will stop the monitoring.
524		631
525	This function is useful when you create e.g. timers or other watchers and	632	This function is useful when you create e.g. timers or other watchers and
526	want to free them when the port gets killed:	633	want to free them when the port gets killed (note the use of C<psub>):
527		634
528	$port->rcv (start => sub {	635	$port->rcv (start => sub {
529	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	636	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
530	undef $timer if 0.9 < rand;	637	undef $timer if 0.9 < rand;
531	});	638	});
532	});	639	});
533		640
534	=cut	641	=cut
…		…
543		650
544	=item kil $port[, @reason]	651	=item kil $port[, @reason]
545		652
546	Kill the specified port with the given C<@reason>.	653	Kill the specified port with the given C<@reason>.
547		654
548	If no C<@reason> is specified, then the port is killed "normally" (linked	655	If no C<@reason> is specified, then the port is killed "normally" (ports
549	ports will not be kileld, or even notified).	656	monitoring other ports will not necessarily die because a port dies
		657	"normally").
550		658
551	Otherwise, linked ports get killed with the same reason (second form of	659	Otherwise, linked ports get killed with the same reason (second form of
552	C<mon>, see below).	660	C<mon>, see above).
553		661
554	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	662	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
555	will be reported as reason C<< die => $@ >>.	663	will be reported as reason C<< die => $@ >>.
556		664
557	Transport/communication errors are reported as C<< transport_error =>	665	Transport/communication errors are reported as C<< transport_error =>
…		…
562	=item $port = spawn $node, $initfunc[, @initdata]	670	=item $port = spawn $node, $initfunc[, @initdata]
563		671
564	Creates a port on the node C<$node> (which can also be a port ID, in which	672	Creates a port on the node C<$node> (which can also be a port ID, in which
565	case it's the node where that port resides).	673	case it's the node where that port resides).
566		674
567	The port ID of the newly created port is return immediately, and it is	675	The port ID of the newly created port is returned immediately, and it is
568	permissible to immediately start sending messages or monitor the port.	676	possible to immediately start sending messages or to monitor the port.
569		677
570	After the port has been created, the init function is	678	After the port has been created, the init function is called on the remote
571	called. This function must be a fully-qualified function name	679	node, in the same context as a C<rcv> callback. This function must be a
572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	680	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
573	program, use C<::name>.	681	specify a function in the main program, use C<::name>.
574		682
575	If the function doesn't exist, then the node tries to C<require>	683	If the function doesn't exist, then the node tries to C<require>
576	the package, then the package above the package and so on (e.g.	684	the package, then the package above the package and so on (e.g.
577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	685	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
578	exists or it runs out of package names.	686	exists or it runs out of package names.
579		687
580	The init function is then called with the newly-created port as context	688	The init function is then called with the newly-created port as context
581	object (C<$SELF>) and the C<@initdata> values as arguments.	689	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		690	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		691	the port might not get created.
582		692
583	A common idiom is to pass your own port, monitor the spawned port, and	693	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	694	port, and in the remote init function, immediately monitor the passed
585	ensures that both ports get cleaned up when there is a problem.	695	local port. This two-way monitoring ensures that both ports get cleaned up
		696	when there is a problem.
		697
		698	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		699	caller before C<spawn> returns (by delaying invocation when spawn is
		700	called for the local node).
586		701
587	Example: spawn a chat server port on C<$othernode>.	702	Example: spawn a chat server port on C<$othernode>.
588		703
589	# this node, executed from within a port context:	704	# this node, executed from within a port context:
590	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	705	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
605		720
606	sub _spawn {	721	sub _spawn {
607	my $port = shift;	722	my $port = shift;
608	my $init = shift;	723	my $init = shift;
609		724
		725	# rcv will create the actual port
610	local $SELF = "$NODE#$port";	726	local $SELF = "$NODE#$port";
611	eval {	727	eval {
612	&{ load_func $init }	728	&{ load_func $init }
613	};	729	};
614	_self_die if $@;	730	_self_die if $@;
615	}	731	}
616		732
617	sub spawn(@) {	733	sub spawn(@) {
618	my ($noderef, undef) = split /#/, shift, 2;	734	my ($nodeid, undef) = split /#/, shift, 2;
619		735
620	my $id = "$RUNIQ." . $ID++;	736	my $id = "$RUNIQ." . $ID++;
621		737
622	$_[0] =~ /::/	738	$_[0] =~ /::/
623	or Carp::croak "spawn init function must be a fully-qualified name, caught";	739	or Carp::croak "spawn init function must be a fully-qualified name, caught";
624		740
625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	741	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
626		742
627	"$noderef#$id"	743	"$nodeid#$id"
628	}	744	}
629		745
630	=item after $timeout, @msg	746	=item after $timeout, @msg
631		747
632	=item after $timeout, $callback	748	=item after $timeout, $callback
633		749
634	Either sends the given message, or call the given callback, after the	750	Either sends the given message, or call the given callback, after the
635	specified number of seconds.	751	specified number of seconds.
636		752
637	This is simply a utility function that come sin handy at times.	753	This is simply a utility function that comes in handy at times - the
		754	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		755	so it may go away in the future.
638		756
639	=cut	757	=cut
640		758
641	sub after($@) {	759	sub after($@) {
642	my ($timeout, @action) = @_;	760	my ($timeout, @action) = @_;
…		…
647	? $action[0]()	765	? $action[0]()
648	: snd @action;	766	: snd @action;
649	};	767	};
650	}	768	}
651		769
		770	=item cal $port, @msg, $callback[, $timeout]
		771
		772	A simple form of RPC - sends a message to the given C<$port> with the
		773	given contents (C<@msg>), but adds a reply port to the message.
		774
		775	The reply port is created temporarily just for the purpose of receiving
		776	the reply, and will be C<kil>ed when no longer needed.
		777
		778	A reply message sent to the port is passed to the C<$callback> as-is.
		779
		780	If an optional time-out (in seconds) is given and it is not C<undef>,
		781	then the callback will be called without any arguments after the time-out
		782	elapsed and the port is C<kil>ed.
		783
		784	If no time-out is given (or it is C<undef>), then the local port will
		785	monitor the remote port instead, so it eventually gets cleaned-up.
		786
		787	Currently this function returns the temporary port, but this "feature"
		788	might go in future versions unless you can make a convincing case that
		789	this is indeed useful for something.
		790
		791	=cut
		792
		793	sub cal(@) {
		794	my $timeout = ref $_[-1] ? undef : pop;
		795	my $cb = pop;
		796
		797	my $port = port {
		798	undef $timeout;
		799	kil $SELF;
		800	&$cb;
		801	};
		802
		803	if (defined $timeout) {
		804	$timeout = AE::timer $timeout, 0, sub {
		805	undef $timeout;
		806	kil $port;
		807	$cb->();
		808	};
		809	} else {
		810	mon $_[0], sub {
		811	kil $port;
		812	$cb->();
		813	};
		814	}
		815
		816	push @_, $port;
		817	&snd;
		818
		819	$port
		820	}
		821
652	=back	822	=back
653		823
654	=head1 AnyEvent::MP vs. Distributed Erlang	824	=head1 AnyEvent::MP vs. Distributed Erlang
655		825
656	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	826	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	827	== 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	828	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
659	sample:	829	sample:
660		830
661	http://www.Erlang.se/doc/programming_rules.shtml	831	http://www.erlang.se/doc/programming_rules.shtml
662	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	832	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	833	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	834	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
665		835
666	Despite the similarities, there are also some important differences:	836	Despite the similarities, there are also some important differences:
667		837
668	=over 4	838	=over 4
669		839
670	=item * Node IDs are arbitrary strings in AEMP.	840	=item * Node IDs are arbitrary strings in AEMP.
671		841
672	Erlang relies on special naming and DNS to work everywhere in the same	842	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	843	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.	844	configuration or DNS), and possibly the addresses of some seed nodes, but
		845	will otherwise discover other nodes (and their IDs) itself.
675		846
676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	847	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
677	uses "local ports are like remote ports".	848	uses "local ports are like remote ports".
678		849
679	The failure modes for local ports are quite different (runtime errors	850	The failure modes for local ports are quite different (runtime errors
…		…
692		863
693	Erlang uses processes that selectively receive messages, and therefore	864	Erlang uses processes that selectively receive messages, and therefore
694	needs a queue. AEMP is event based, queuing messages would serve no	865	needs a queue. AEMP is event based, queuing messages would serve no
695	useful purpose. For the same reason the pattern-matching abilities of	866	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	867	AnyEvent::MP are more limited, as there is little need to be able to
697	filter messages without dequeing them.	868	filter messages without dequeuing them.
698		869
699	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	870	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
700		871
701	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	872	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
702		873
…		…
704	so does not need a queue that can overflow). AEMP sends are immediate,	875	so does not need a queue that can overflow). AEMP sends are immediate,
705	connection establishment is handled in the background.	876	connection establishment is handled in the background.
706		877
707	=item * Erlang suffers from silent message loss, AEMP does not.	878	=item * Erlang suffers from silent message loss, AEMP does not.
708		879
709	Erlang makes few guarantees on messages delivery - messages can get lost	880	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,	881	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).	882	b, and c, and the other side only receives messages a and c).
712		883
713	AEMP guarantees correct ordering, and the guarantee that after one message	884	AEMP guarantees correct ordering, and the guarantee that after one message
714	is lost, all following ones sent to the same port are lost as well, until	885	is lost, all following ones sent to the same port are lost as well, until
715	monitoring raises an error, so there are no silent "holes" in the message	886	monitoring raises an error, so there are no silent "holes" in the message
716	sequence.	887	sequence.
…		…
733	=item * The AEMP protocol is optimised for both text-based and binary	904	=item * The AEMP protocol is optimised for both text-based and binary
734	communications.	905	communications.
735		906
736	The AEMP protocol, unlike the Erlang protocol, supports both programming	907	The AEMP protocol, unlike the Erlang protocol, supports both programming
737	language independent text-only protocols (good for debugging) and binary,	908	language independent text-only protocols (good for debugging) and binary,
738	language-specific serialisers (e.g. Storable).	909	language-specific serialisers (e.g. Storable). By default, unless TLS is
		910	used, the protocol is actually completely text-based.
739		911
740	It has also been carefully designed to be implementable in other languages	912	It has also been carefully designed to be implementable in other languages
741	with a minimum of work while gracefully degrading functionality to make the	913	with a minimum of work while gracefully degrading functionality to make the
742	protocol simple.	914	protocol simple.
743		915
…		…
749	Erlang, as one can choose between automatic kill, exit message or callback	921	Erlang, as one can choose between automatic kill, exit message or callback
750	on a per-process basis.	922	on a per-process basis.
751		923
752	=item * Erlang tries to hide remote/local connections, AEMP does not.	924	=item * Erlang tries to hide remote/local connections, AEMP does not.
753		925
754	Monitoring in Erlang is not an indicator of process death/crashes,	926	Monitoring in Erlang is not an indicator of process death/crashes, in the
755	as linking is (except linking is unreliable in Erlang).	927	same way as linking is (except linking is unreliable in Erlang).
756		928
757	In AEMP, you don't "look up" registered port names or send to named ports	929	In AEMP, you don't "look up" registered port names or send to named ports
758	that might or might not be persistent. Instead, you normally spawn a port	930	that might or might not be persistent. Instead, you normally spawn a port
759	on the remote node. The init function monitors the you, and you monitor	931	on the remote node. The init function monitors you, and you monitor the
760	the remote port. Since both monitors are local to the node, they are much	932	remote port. Since both monitors are local to the node, they are much more
761	more reliable.	933	reliable (no need for C<spawn_link>).
762		934
763	This also saves round-trips and avoids sending messages to the wrong port	935	This also saves round-trips and avoids sending messages to the wrong port
764	(hard to do in Erlang).	936	(hard to do in Erlang).
765		937
766	=back	938	=back
767		939
768	=head1 RATIONALE	940	=head1 RATIONALE
769		941
770	=over 4	942	=over 4
771		943
772	=item Why strings for ports and noderefs, why not objects?	944	=item Why strings for port and node IDs, why not objects?
773		945
774	We considered "objects", but found that the actual number of methods	946	We considered "objects", but found that the actual number of methods
775	thatc an be called are very low. Since port IDs and noderefs travel over	947	that can be called are quite low. Since port and node IDs travel over
776	the network frequently, the serialising/deserialising would add lots of	948	the network frequently, the serialising/deserialising would add lots of
777	overhead, as well as having to keep a proxy object.	949	overhead, as well as having to keep a proxy object everywhere.
778		950
779	Strings can easily be printed, easily serialised etc. and need no special	951	Strings can easily be printed, easily serialised etc. and need no special
780	procedures to be "valid".	952	procedures to be "valid".
781		953
782	And a a miniport consists of a single closure stored in a global hash - it	954	And as a result, a miniport consists of a single closure stored in a
783	can't become much cheaper.	955	global hash - it can't become much cheaper.
784		956
785	=item Why favour JSON, why not real serialising format such as Storable?	957	=item Why favour JSON, why not a real serialising format such as Storable?
786		958
787	In fact, any AnyEvent::MP node will happily accept Storable as framing	959	In fact, any AnyEvent::MP node will happily accept Storable as framing
788	format, but currently there is no way to make a node use Storable by	960	format, but currently there is no way to make a node use Storable by
789	default.	961	default (although all nodes will accept it).
790		962
791	The default framing protocol is JSON because a) JSON::XS is many times	963	The default framing protocol is JSON because a) JSON::XS is many times
792	faster for small messages and b) most importantly, after years of	964	faster for small messages and b) most importantly, after years of
793	experience we found that object serialisation is causing more problems	965	experience we found that object serialisation is causing more problems
794	than it gains: Just like function calls, objects simply do not travel	966	than it solves: Just like function calls, objects simply do not travel
795	easily over the network, mostly because they will always be a copy, so you	967	easily over the network, mostly because they will always be a copy, so you
796	always have to re-think your design.	968	always have to re-think your design.
797		969
798	Keeping your messages simple, concentrating on data structures rather than	970	Keeping your messages simple, concentrating on data structures rather than
799	objects, will keep your messages clean, tidy and efficient.	971	objects, will keep your messages clean, tidy and efficient.
800		972
801	=back	973	=back
802		974
803	=head1 SEE ALSO	975	=head1 SEE ALSO
804		976
		977	L<AnyEvent::MP::Intro> - a gentle introduction.
		978
		979	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		980
		981	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		982	your applications.
		983
		984	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		985	all nodes.
		986
805	L<AnyEvent>.	987	L<AnyEvent>.
806		988
807	=head1 AUTHOR	989	=head1 AUTHOR
808		990
809	Marc Lehmann <schmorp@schmorp.de>	991	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC vs. Revision 1.103 by root, Sat Oct 17 01:42:39 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.66 by root, Fri Aug 28 01:07:24 2009 UTC vs.
Revision 1.103 by root, Sat Oct 17 01:42:39 2009 UTC