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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.57 by root, Sat Aug 15 04:34:34 2009 UTC vs.
Revision 1.90 by root, Tue Sep 22 09:38:28 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; # -OR-	15	configure;
17	initialise_node "localhost:4040"; # -OR-
18	initialise_node "slave/", "localhost:4040"
19		16
20	# ports are message endpoints	17	# ports are message destinations
21		18
22	# sending messages	19	# sending messages
23	snd $port, type => data...;	20	snd $port, type => data...;
24	snd $port, @msg;	21	snd $port, @msg;
25	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
26		23
27	# creating/using ports, the simple way	24	# creating/using ports, the simple way
28	my $simple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
29		26
30	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
31	my $port = port;	28	my $port = port;
32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
33	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
34		31
35	# create a port on another node	32	# create a port on another node
36	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
37		34
38	# monitoring	35	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $localport, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	37	mon $localport, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	38	mon $localport, $otherport, @msg # send message on death
42		39
43	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
44		41
		42	bin/aemp - stable.
45	AnyEvent::MP - stable API, should work	43	AnyEvent::MP - stable API, should work.
46	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.
47	AnyEvent::MP::Kernel - WIP
48	AnyEvent::MP::Transport - mostly stable	45	AnyEvent::MP::Kernel - mostly stable API.
49		46	AnyEvent::MP::Global - stable API.
50	stay tuned.
51		47
52	=head1 DESCRIPTION	48	=head1 DESCRIPTION
53		49
54	This module (-family) implements a simple message passing framework.	50	This module (-family) implements a simple message passing framework.
55		51
56	Despite its simplicity, you can securely message other processes running	52	Despite its simplicity, you can securely message other processes running
57	on the same or other hosts.	53	on the same or other hosts, and you can supervise entities remotely.
58		54
59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	55	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60	manual page.	56	manual page and the examples under F<eg/>.
61
62	At the moment, this module family is severly broken and underdocumented,
63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
64	stay tuned!
65		57
66	=head1 CONCEPTS	58	=head1 CONCEPTS
67		59
68	=over 4	60	=over 4
69		61
70	=item port	62	=item port
71		63
72	A port is something you can send messages to (with the C<snd> function).	64	Not to be confused with a TCP port, a "port" is something you can send
		65	messages to (with the C<snd> function).
73		66
74	Ports allow you to register C<rcv> handlers that can match all or just	67	Ports allow you to register C<rcv> handlers that can match all or just
75	some messages. Messages will not be queued.	68	some messages. Messages send to ports will not be queued, regardless of
		69	anything was listening for them or not.
76		70
77	=item port id - C<noderef#portname>	71	=item port ID - C<nodeid#portname>
78		72
79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as	73	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
80	separator, and a port name (a printable string of unspecified format). An	74	separator, and a port name (a printable string of unspecified format).
81	exception is the the node port, whose ID is identical to its node
82	reference.
83		75
84	=item node	76	=item node
85		77
86	A node is a single process containing at least one port - the node port,	78	A node is a single process containing at least one port - the node port,
87	which provides nodes to manage each other remotely, and to create new	79	which enables nodes to manage each other remotely, and to create new
88	ports.	80	ports.
89		81
90	Nodes are either private (single-process only), slaves (connected to a	82	Nodes are either public (have one or more listening ports) or private
91	master node only) or public nodes (connectable from unrelated nodes).	83	(no listening ports). Private nodes cannot talk to other private nodes
		84	currently.
92		85
93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
94		87
95	A node reference is a string that either simply identifies the node (for	88	A node ID is a string that uniquely identifies the node within a
96	private and slave nodes), or contains a recipe on how to reach a given	89	network. Depending on the configuration used, node IDs can look like a
97	node (for public nodes).	90	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		91	doesn't interpret node IDs in any way.
98		92
99	This recipe is simply a comma-separated list of C<address:port> pairs (for	93	=item binds - C<ip:port>
100	TCP/IP, other protocols might look different).
101		94
102	Node references come in two flavours: resolved (containing only numerical	95	Nodes can only talk to each other by creating some kind of connection to
103	addresses) or unresolved (where hostnames are used instead of addresses).	96	each other. To do this, nodes should listen on one or more local transport
		97	endpoints - binds. Currently, only standard C<ip:port> specifications can
		98	be used, which specify TCP ports to listen on.
104		99
105	Before using an unresolved node reference in a message you first have to	100	=item seed nodes
106	resolve it.	101
		102	When a node starts, it knows nothing about the network. To teach the node
		103	about the network it first has to contact some other node within the
		104	network. This node is called a seed.
		105
		106	Apart from the fact that other nodes know them as seed nodes and they have
		107	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		108	any node can function as a seed node for others.
		109
		110	In addition to discovering the network, seed nodes are also used to
		111	maintain the network and to connect nodes that otherwise would have
		112	trouble connecting. They form the backbone of an AnyEvent::MP network.
		113
		114	Seed nodes are expected to be long-running, and at least one seed node
		115	should always be available. They should also be relatively responsive - a
		116	seed node that blocks for long periods will slow down everybody else.
		117
		118	=item seeds - C<host:port>
		119
		120	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		121	TCP port) of nodes thta should be used as seed nodes.
		122
		123	The nodes listening on those endpoints are expected to be long-running,
		124	and at least one of those should always be available. When nodes run out
		125	of connections (e.g. due to a network error), they try to re-establish
		126	connections to some seednodes again to join the network.
107		127
108	=back	128	=back
109		129
110	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
111		131
126	use base "Exporter";	146	use base "Exporter";
127		147
128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	148	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
129		149
130	our @EXPORT = qw(	150	our @EXPORT = qw(
131	NODE $NODE *SELF node_of _any_	151	NODE $NODE *SELF node_of after
132	resolve_node initialise_node	152	configure
133	snd rcv mon kil reg psub spawn	153	snd rcv mon mon_guard kil reg psub spawn cal
134	port	154	port
135	);	155	);
136		156
137	our $SELF;	157	our $SELF;
138		158
…		…
142	kil $SELF, die => $msg;	162	kil $SELF, die => $msg;
143	}	163	}
144		164
145	=item $thisnode = NODE / $NODE	165	=item $thisnode = NODE / $NODE
146		166
147	The C<NODE> function returns, and the C<$NODE> variable contains the	167	The C<NODE> function returns, and the C<$NODE> variable contains, the node
148	noderef of the local node. The value is initialised by a call to	168	ID of the node running in the current process. This value is initialised by
149	C<initialise_node>.	169	a call to C<configure>.
150		170
151	=item $noderef = node_of $port	171	=item $nodeid = node_of $port
152		172
153	Extracts and returns the noderef from a port ID or a noderef.	173	Extracts and returns the node ID from a port ID or a node ID.
154		174
155	=item initialise_node $noderef, $seednode, $seednode...	175	=item configure $profile, key => value...
156		176
157	=item initialise_node "slave/", $master, $master...	177	=item configure key => value...
158		178
159	Before a node can talk to other nodes on the network it has to initialise	179	Before a node can talk to other nodes on the network (i.e. enter
160	itself - the minimum a node needs to know is it's own name, and optionally	180	"distributed mode") it has to configure itself - the minimum a node needs
161	it should know the noderefs of some other nodes in the network.	181	to know is its own name, and optionally it should know the addresses of
		182	some other nodes in the network to discover other nodes.
162		183
163	This function initialises a node - it must be called exactly once (or	184	This function configures a node - it must be called exactly once (or
164	never) before calling other AnyEvent::MP functions.	185	never) before calling other AnyEvent::MP functions.
165		186
166	All arguments (optionally except for the first) are noderefs, which can be
167	either resolved or unresolved.
168
169	The first argument will be looked up in the configuration database first
170	(if it is C<undef> then the current nodename will be used instead) to find
171	the relevant configuration profile (see L<aemp>). If none is found then
172	the default configuration is used. The configuration supplies additional
173	seed/master nodes and can override the actual noderef.
174
175	There are two types of networked nodes, public nodes and slave nodes:
176
177	=over 4	187	=over 4
178		188
179	=item public nodes	189	=item step 1, gathering configuration from profiles
180		190
181	For public nodes, C<$noderef> (supplied either directly to	191	The function first looks up a profile in the aemp configuration (see the
182	C<initialise_node> or indirectly via a profile or the nodename) must be a	192	L<aemp> commandline utility). The profile name can be specified via the
183	noderef (possibly unresolved, in which case it will be resolved).	193	named C<profile> parameter or can simply be the first parameter). If it is
		194	missing, then the nodename (F<uname -n>) will be used as profile name.
184		195
185	After resolving, the node will bind itself on all endpoints and try to	196	The profile data is then gathered as follows:
186	connect to all additional C<$seednodes> that are specified. Seednodes are
187	optional and can be used to quickly bootstrap the node into an existing
188	network.
189		197
190	=item slave nodes	198	First, all remaining key => value pairs (all of which are conveniently
		199	undocumented at the moment) will be interpreted as configuration
		200	data. Then they will be overwritten by any values specified in the global
		201	default configuration (see the F<aemp> utility), then the chain of
		202	profiles chosen by the profile name (and any C<parent> attributes).
191		203
192	When the C<$noderef> (either as given or overriden by the config file)	204	That means that the values specified in the profile have highest priority
193	is the special string C<slave/>, then the node will become a slave	205	and the values specified directly via C<configure> have lowest priority,
194	node. Slave nodes cannot be contacted from outside and will route most of	206	and can only be used to specify defaults.
195	their traffic to the master node that they attach to.
196		207
197	At least one additional noderef is required (either by specifying it	208	If the profile specifies a node ID, then this will become the node ID of
198	directly or because it is part of the configuration profile): The node	209	this process. If not, then the profile name will be used as node ID. The
199	will try to connect to all of them and will become a slave attached to the	210	special node ID of C<anon/> will be replaced by a random node ID.
200	first node it can successfully connect to.
201		211
202	Note that slave nodes cannot change their name, and consequently, their	212	=item step 2, bind listener sockets
203	master, so if the master goes down, the slave node will not function well	213
204	anymore until it can re-establish conenciton to its master. This makes	214	The next step is to look up the binds in the profile, followed by binding
205	slave nodes unsuitable for long-term nodes or fault-tolerant networks.	215	aemp protocol listeners on all binds specified (it is possible and valid
		216	to have no binds, meaning that the node cannot be contacted form the
		217	outside. This means the node cannot talk to other nodes that also have no
		218	binds, but it can still talk to all "normal" nodes).
		219
		220	If the profile does not specify a binds list, then a default of C<*> is
		221	used, meaning the node will bind on a dynamically-assigned port on every
		222	local IP address it finds.
		223
		224	=item step 3, connect to seed nodes
		225
		226	As the last step, the seeds list from the profile is passed to the
		227	L<AnyEvent::MP::Global> module, which will then use it to keep
		228	connectivity with at least one node at any point in time.
206		229
207	=back	230	=back
208		231
209	This function will block until all nodes have been resolved and, for slave	232	Example: become a distributed node using the local node name as profile.
210	nodes, until it has successfully established a connection to a master	233	This should be the most common form of invocation for "daemon"-type nodes.
211	server.
212		234
213	All the seednodes will also be specially marked to automatically retry	235	configure
214	connecting to them infinitely.
215		236
216	Example: become a public node listening on the guessed noderef, or the one	237	Example: become an anonymous node. This form is often used for commandline
217	specified via C<aemp> for the current node. This should be the most common	238	clients.
218	form of invocation for "daemon"-type nodes.
219		239
220	initialise_node;	240	configure nodeid => "anon/";
221		241
222	Example: become a slave node to any of the the seednodes specified via	242	Example: configure a node using a profile called seed, which si suitable
223	C<aemp>. This form is often used for commandline clients.	243	for a seed node as it binds on all local addresses on a fixed port (4040,
		244	customary for aemp).
224		245
225	initialise_node "slave/";	246	# use the aemp commandline utility
		247	# aemp profile seed nodeid anon/ binds '*:4040'
226		248
227	Example: become a slave node to any of the specified master servers. This	249	# then use it
228	form is also often used for commandline clients.	250	configure profile => "seed";
229		251
230	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";	252	# or simply use aemp from the shell again:
		253	# aemp run profile seed
231		254
232	Example: become a public node, and try to contact some well-known master	255	# or provide a nicer-to-remember nodeid
233	servers to become part of the network.	256	# aemp run profile seed nodeid "$(hostname)"
234
235	initialise_node undef, "master1", "master2";
236
237	Example: become a public node listening on port C<4041>.
238
239	initialise_node 4041;
240
241	Example: become a public node, only visible on localhost port 4044.
242
243	initialise_node "localhost:4044";
244
245	=item $cv = resolve_node $noderef
246
247	Takes an unresolved node reference that may contain hostnames and
248	abbreviated IDs, resolves all of them and returns a resolved node
249	reference.
250
251	In addition to C<address:port> pairs allowed in resolved noderefs, the
252	following forms are supported:
253
254	=over 4
255
256	=item the empty string
257
258	An empty-string component gets resolved as if the default port (4040) was
259	specified.
260
261	=item naked port numbers (e.g. C<1234>)
262
263	These are resolved by prepending the local nodename and a colon, to be
264	further resolved.
265
266	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
267
268	These are resolved by using AnyEvent::DNS to resolve them, optionally
269	looking up SRV records for the C<aemp=4040> port, if no port was
270	specified.
271
272	=back
273		257
274	=item $SELF	258	=item $SELF
275		259
276	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
277	blocks.	261	blocks.
278		262
279	=item SELF, %SELF, @SELF...	263	=item *SELF, SELF, %SELF, @SELF...
280		264
281	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
282	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols named C<SELF> are exported by this
283	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
284		268
285	=item snd $port, type => @data	269	=item snd $port, type => @data
286		270
287	=item snd $port, @msg	271	=item snd $port, @msg
288		272
289	Send the given message to the given port ID, which can identify either	273	Send the given message to the given port, which can identify either a
290	a local or a remote port, and must be a port ID.	274	local or a remote port, and must be a port ID.
291		275
292	While the message can be about anything, it is highly recommended to use a	276	While the message can be almost anything, it is highly recommended to
293	string as first element (a port ID, or some word that indicates a request	277	use a string as first element (a port ID, or some word that indicates a
294	type etc.).	278	request type etc.) and to consist if only simple perl values (scalars,
		279	arrays, hashes) - if you think you need to pass an object, think again.
295		280
296	The message data effectively becomes read-only after a call to this	281	The message data logically becomes read-only after a call to this
297	function: modifying any argument is not allowed and can cause many	282	function: modifying any argument (or values referenced by them) is
298	problems.	283	forbidden, as there can be considerable time between the call to C<snd>
		284	and the time the message is actually being serialised - in fact, it might
		285	never be copied as within the same process it is simply handed to the
		286	receiving port.
299		287
300	The type of data you can transfer depends on the transport protocol: when	288	The type of data you can transfer depends on the transport protocol: when
301	JSON is used, then only strings, numbers and arrays and hashes consisting	289	JSON is used, then only strings, numbers and arrays and hashes consisting
302	of those are allowed (no objects). When Storable is used, then anything	290	of those are allowed (no objects). When Storable is used, then anything
303	that Storable can serialise and deserialise is allowed, and for the local	291	that Storable can serialise and deserialise is allowed, and for the local
304	node, anything can be passed.	292	node, anything can be passed. Best rely only on the common denominator of
		293	these.
305		294
306	=item $local_port = port	295	=item $local_port = port
307		296
308	Create a new local port object and returns its port ID. Initially it has	297	Create a new local port object and returns its port ID. Initially it has
309	no callbacks set and will throw an error when it receives messages.	298	no callbacks set and will throw an error when it receives messages.
…		…
394		383
395	=cut	384	=cut
396		385
397	sub rcv($@) {	386	sub rcv($@) {
398	my $port = shift;	387	my $port = shift;
399	my ($noderef, $portid) = split /#/, $port, 2;	388	my ($nodeid, $portid) = split /#/, $port, 2;
400		389
401	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	390	$NODE{$nodeid} == $NODE{""}
402	or Carp::croak "$port: rcv can only be called on local ports, caught";	391	or Carp::croak "$port: rcv can only be called on local ports, caught";
403		392
404	while (@_) {	393	while (@_) {
405	if (ref $_[0]) {	394	if (ref $_[0]) {
406	if (my $self = $PORT_DATA{$portid}) {	395	if (my $self = $PORT_DATA{$portid}) {
…		…
485	$res	474	$res
486	}	475	}
487	}	476	}
488	}	477	}
489		478
490	=item $guard = mon $port, $cb->(@reason)	479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
491		480
492	=item $guard = mon $port, $rcvport	481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
493		482
494	=item $guard = mon $port	483	=item $guard = mon $port # kill $SELF when $port dies
495		484
496	=item $guard = mon $port, $rcvport, @msg	485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
497		486
498	Monitor the given port and do something when the port is killed or	487	Monitor the given port and do something when the port is killed or
499	messages to it were lost, and optionally return a guard that can be used	488	messages to it were lost, and optionally return a guard that can be used
500	to stop monitoring again.	489	to stop monitoring again.
501
502	C<mon> effectively guarantees that, in the absence of hardware failures,
503	that after starting the monitor, either all messages sent to the port
504	will arrive, or the monitoring action will be invoked after possible
505	message loss has been detected. No messages will be lost "in between"
506	(after the first lost message no further messages will be received by the
507	port). After the monitoring action was invoked, further messages might get
508	delivered again.
509		490
510	In the first form (callback), the callback is simply called with any	491	In the first form (callback), the callback is simply called with any
511	number of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
512	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
513	C<eval> if unsure.	494	C<eval> if unsure.
514		495
515	In the second form (another port given), the other port (C<$rcvport>)	496	In the second form (another port given), the other port (C<$rcvport>)
516	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
517	"normal" kils nothing happens, while under all other conditions, the other	498	"normal" kils nothing happens, while under all other conditions, the other
518	port is killed with the same reason.	499	port is killed with the same reason.
519		500
520	The third form (kill self) is the same as the second form, except that	501	The third form (kill self) is the same as the second form, except that
521	C<$rvport> defaults to C<$SELF>.	502	C<$rvport> defaults to C<$SELF>.
522		503
523	In the last form (message), a message of the form C<@msg, @reason> will be	504	In the last form (message), a message of the form C<@msg, @reason> will be
524	C<snd>.	505	C<snd>.
		506
		507	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		508	alert was raised), they are removed and will not trigger again.
525		509
526	As a rule of thumb, monitoring requests should always monitor a port from	510	As a rule of thumb, monitoring requests should always monitor a port from
527	a local port (or callback). The reason is that kill messages might get	511	a local port (or callback). The reason is that kill messages might get
528	lost, just like any other message. Another less obvious reason is that	512	lost, just like any other message. Another less obvious reason is that
529	even monitoring requests can get lost (for exmaple, when the connection	513	even monitoring requests can get lost (for example, when the connection
530	to the other node goes down permanently). When monitoring a port locally	514	to the other node goes down permanently). When monitoring a port locally
531	these problems do not exist.	515	these problems do not exist.
532		516
		517	C<mon> effectively guarantees that, in the absence of hardware failures,
		518	after starting the monitor, either all messages sent to the port will
		519	arrive, or the monitoring action will be invoked after possible message
		520	loss has been detected. No messages will be lost "in between" (after
		521	the first lost message no further messages will be received by the
		522	port). After the monitoring action was invoked, further messages might get
		523	delivered again.
		524
		525	Inter-host-connection timeouts and monitoring depend on the transport
		526	used. The only transport currently implemented is TCP, and AnyEvent::MP
		527	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		528	non-idle connection, and usually around two hours for idle conenctions).
		529
		530	This means that monitoring is good for program errors and cleaning up
		531	stuff eventually, but they are no replacement for a timeout when you need
		532	to ensure some maximum latency.
		533
533	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
534		535
535	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
536		537
537	Example: kill ourselves when C<$port> is killed abnormally.	538	Example: kill ourselves when C<$port> is killed abnormally.
…		…
543	mon $port, $self => "restart";	544	mon $port, $self => "restart";
544		545
545	=cut	546	=cut
546		547
547	sub mon {	548	sub mon {
548	my ($noderef, $port) = split /#/, shift, 2;	549	my ($nodeid, $port) = split /#/, shift, 2;
549		550
550	my $node = $NODE{$noderef} \|\| add_node $noderef;	551	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
551		552
552	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	553	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
553		554
554	unless (ref $cb) {	555	unless (ref $cb) {
555	if (@_) {	556	if (@_) {
…		…
575	is killed, the references will be freed.	576	is killed, the references will be freed.
576		577
577	Optionally returns a guard that will stop the monitoring.	578	Optionally returns a guard that will stop the monitoring.
578		579
579	This function is useful when you create e.g. timers or other watchers and	580	This function is useful when you create e.g. timers or other watchers and
580	want to free them when the port gets killed:	581	want to free them when the port gets killed (note the use of C<psub>):
581		582
582	$port->rcv (start => sub {	583	$port->rcv (start => sub {
583	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	584	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
584	undef $timer if 0.9 < rand;	585	undef $timer if 0.9 < rand;
585	});	586	});
586	});	587	});
587		588
588	=cut	589	=cut
…		…
597		598
598	=item kil $port[, @reason]	599	=item kil $port[, @reason]
599		600
600	Kill the specified port with the given C<@reason>.	601	Kill the specified port with the given C<@reason>.
601		602
602	If no C<@reason> is specified, then the port is killed "normally" (linked	603	If no C<@reason> is specified, then the port is killed "normally" (ports
603	ports will not be kileld, or even notified).	604	monitoring other ports will not necessarily die because a port dies
		605	"normally").
604		606
605	Otherwise, linked ports get killed with the same reason (second form of	607	Otherwise, linked ports get killed with the same reason (second form of
606	C<mon>, see below).	608	C<mon>, see above).
607		609
608	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	610	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
609	will be reported as reason C<< die => $@ >>.	611	will be reported as reason C<< die => $@ >>.
610		612
611	Transport/communication errors are reported as C<< transport_error =>	613	Transport/communication errors are reported as C<< transport_error =>
…		…
616	=item $port = spawn $node, $initfunc[, @initdata]	618	=item $port = spawn $node, $initfunc[, @initdata]
617		619
618	Creates a port on the node C<$node> (which can also be a port ID, in which	620	Creates a port on the node C<$node> (which can also be a port ID, in which
619	case it's the node where that port resides).	621	case it's the node where that port resides).
620		622
621	The port ID of the newly created port is return immediately, and it is	623	The port ID of the newly created port is returned immediately, and it is
622	permissible to immediately start sending messages or monitor the port.	624	possible to immediately start sending messages or to monitor the port.
623		625
624	After the port has been created, the init function is	626	After the port has been created, the init function is called on the remote
625	called. This function must be a fully-qualified function name	627	node, in the same context as a C<rcv> callback. This function must be a
626	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	628	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
627	program, use C<::name>.	629	specify a function in the main program, use C<::name>.
628		630
629	If the function doesn't exist, then the node tries to C<require>	631	If the function doesn't exist, then the node tries to C<require>
630	the package, then the package above the package and so on (e.g.	632	the package, then the package above the package and so on (e.g.
631	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	633	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
632	exists or it runs out of package names.	634	exists or it runs out of package names.
633		635
634	The init function is then called with the newly-created port as context	636	The init function is then called with the newly-created port as context
635	object (C<$SELF>) and the C<@initdata> values as arguments.	637	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		638	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		639	the port might not get created.
636		640
637	A common idiom is to pass your own port, monitor the spawned port, and	641	A common idiom is to pass a local port, immediately monitor the spawned
638	in the init function, monitor the original port. This two-way monitoring	642	port, and in the remote init function, immediately monitor the passed
639	ensures that both ports get cleaned up when there is a problem.	643	local port. This two-way monitoring ensures that both ports get cleaned up
		644	when there is a problem.
		645
		646	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		647	caller before C<spawn> returns (by delaying invocation when spawn is
		648	called for the local node).
640		649
641	Example: spawn a chat server port on C<$othernode>.	650	Example: spawn a chat server port on C<$othernode>.
642		651
643	# this node, executed from within a port context:	652	# this node, executed from within a port context:
644	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
659		668
660	sub _spawn {	669	sub _spawn {
661	my $port = shift;	670	my $port = shift;
662	my $init = shift;	671	my $init = shift;
663		672
		673	# rcv will create the actual port
664	local $SELF = "$NODE#$port";	674	local $SELF = "$NODE#$port";
665	eval {	675	eval {
666	&{ load_func $init }	676	&{ load_func $init }
667	};	677	};
668	_self_die if $@;	678	_self_die if $@;
669	}	679	}
670		680
671	sub spawn(@) {	681	sub spawn(@) {
672	my ($noderef, undef) = split /#/, shift, 2;	682	my ($nodeid, undef) = split /#/, shift, 2;
673		683
674	my $id = "$RUNIQ." . $ID++;	684	my $id = "$RUNIQ." . $ID++;
675		685
676	$_[0] =~ /::/	686	$_[0] =~ /::/
677	or Carp::croak "spawn init function must be a fully-qualified name, caught";	687	or Carp::croak "spawn init function must be a fully-qualified name, caught";
678		688
679	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
680		690
681	"$noderef#$id"	691	"$nodeid#$id"
		692	}
		693
		694	=item after $timeout, @msg
		695
		696	=item after $timeout, $callback
		697
		698	Either sends the given message, or call the given callback, after the
		699	specified number of seconds.
		700
		701	This is simply a utility function that comes in handy at times - the
		702	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		703	so it may go away in the future.
		704
		705	=cut
		706
		707	sub after($@) {
		708	my ($timeout, @action) = @_;
		709
		710	my $t; $t = AE::timer $timeout, 0, sub {
		711	undef $t;
		712	ref $action[0]
		713	? $action[0]()
		714	: snd @action;
		715	};
		716	}
		717
		718	=item cal $port, @msg, $callback[, $timeout]
		719
		720	A simple form of RPC - sends a message to the given C<$port> with the
		721	given contents (C<@msg>), but adds a reply port to the message.
		722
		723	The reply port is created temporarily just for the purpose of receiving
		724	the reply, and will be C<kil>ed when no longer needed.
		725
		726	A reply message sent to the port is passed to the C<$callback> as-is.
		727
		728	If an optional time-out (in seconds) is given and it is not C<undef>,
		729	then the callback will be called without any arguments after the time-out
		730	elapsed and the port is C<kil>ed.
		731
		732	If no time-out is given, then the local port will monitor the remote port
		733	instead, so it eventually gets cleaned-up.
		734
		735	Currently this function returns the temporary port, but this "feature"
		736	might go in future versions unless you can make a convincing case that
		737	this is indeed useful for something.
		738
		739	=cut
		740
		741	sub cal(@) {
		742	my $timeout = ref $_[-1] ? undef : pop;
		743	my $cb = pop;
		744
		745	my $port = port {
		746	undef $timeout;
		747	kil $SELF;
		748	&$cb;
		749	};
		750
		751	if (defined $timeout) {
		752	$timeout = AE::timer $timeout, 0, sub {
		753	undef $timeout;
		754	kil $port;
		755	$cb->();
		756	};
		757	} else {
		758	mon $_[0], sub {
		759	kil $port;
		760	$cb->();
		761	};
		762	}
		763
		764	push @_, $port;
		765	&snd;
		766
		767	$port
682	}	768	}
683		769
684	=back	770	=back
685		771
686	=head1 AnyEvent::MP vs. Distributed Erlang	772	=head1 AnyEvent::MP vs. Distributed Erlang
…		…
697		783
698	Despite the similarities, there are also some important differences:	784	Despite the similarities, there are also some important differences:
699		785
700	=over 4	786	=over 4
701		787
702	=item * Node references contain the recipe on how to contact them.	788	=item * Node IDs are arbitrary strings in AEMP.
703		789
704	Erlang relies on special naming and DNS to work everywhere in the	790	Erlang relies on special naming and DNS to work everywhere in the same
705	same way. AEMP relies on each node knowing it's own address(es), with	791	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
706	convenience functionality.	792	configuration or DNS), but will otherwise discover other odes itself.
707
708	This means that AEMP requires a less tightly controlled environment at the
709	cost of longer node references and a slightly higher management overhead.
710		793
711	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	794	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
712	uses "local ports are like remote ports".	795	uses "local ports are like remote ports".
713		796
714	The failure modes for local ports are quite different (runtime errors	797	The failure modes for local ports are quite different (runtime errors
…		…
727		810
728	Erlang uses processes that selectively receive messages, and therefore	811	Erlang uses processes that selectively receive messages, and therefore
729	needs a queue. AEMP is event based, queuing messages would serve no	812	needs a queue. AEMP is event based, queuing messages would serve no
730	useful purpose. For the same reason the pattern-matching abilities of	813	useful purpose. For the same reason the pattern-matching abilities of
731	AnyEvent::MP are more limited, as there is little need to be able to	814	AnyEvent::MP are more limited, as there is little need to be able to
732	filter messages without dequeing them.	815	filter messages without dequeuing them.
733		816
734	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	817	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
735		818
736	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	819	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
737		820
…		…
743		826
744	Erlang makes few guarantees on messages delivery - messages can get lost	827	Erlang makes few guarantees on messages delivery - messages can get lost
745	without any of the processes realising it (i.e. you send messages a, b,	828	without any of the processes realising it (i.e. you send messages a, b,
746	and c, and the other side only receives messages a and c).	829	and c, and the other side only receives messages a and c).
747		830
748	AEMP guarantees correct ordering, and the guarantee that there are no	831	AEMP guarantees correct ordering, and the guarantee that after one message
749	holes in the message sequence.	832	is lost, all following ones sent to the same port are lost as well, until
750		833	monitoring raises an error, so there are no silent "holes" in the message
751	=item * In Erlang, processes can be declared dead and later be found to be	834	sequence.
752	alive.
753
754	In Erlang it can happen that a monitored process is declared dead and
755	linked processes get killed, but later it turns out that the process is
756	still alive - and can receive messages.
757
758	In AEMP, when port monitoring detects a port as dead, then that port will
759	eventually be killed - it cannot happen that a node detects a port as dead
760	and then later sends messages to it, finding it is still alive.
761		835
762	=item * Erlang can send messages to the wrong port, AEMP does not.	836	=item * Erlang can send messages to the wrong port, AEMP does not.
763		837
764	In Erlang it is quite likely that a node that restarts reuses a process ID	838	In Erlang it is quite likely that a node that restarts reuses a process ID
765	known to other nodes for a completely different process, causing messages	839	known to other nodes for a completely different process, causing messages
…		…
769	around in the network will not be sent to an unrelated port.	843	around in the network will not be sent to an unrelated port.
770		844
771	=item * Erlang uses unprotected connections, AEMP uses secure	845	=item * Erlang uses unprotected connections, AEMP uses secure
772	authentication and can use TLS.	846	authentication and can use TLS.
773		847
774	AEMP can use a proven protocol - SSL/TLS - to protect connections and	848	AEMP can use a proven protocol - TLS - to protect connections and
775	securely authenticate nodes.	849	securely authenticate nodes.
776		850
777	=item * The AEMP protocol is optimised for both text-based and binary	851	=item * The AEMP protocol is optimised for both text-based and binary
778	communications.	852	communications.
779		853
780	The AEMP protocol, unlike the Erlang protocol, supports both	854	The AEMP protocol, unlike the Erlang protocol, supports both programming
781	language-independent text-only protocols (good for debugging) and binary,	855	language independent text-only protocols (good for debugging) and binary,
782	language-specific serialisers (e.g. Storable).	856	language-specific serialisers (e.g. Storable). By default, unless TLS is
		857	used, the protocol is actually completely text-based.
783		858
784	It has also been carefully designed to be implementable in other languages	859	It has also been carefully designed to be implementable in other languages
785	with a minimum of work while gracefully degrading fucntionality to make the	860	with a minimum of work while gracefully degrading functionality to make the
786	protocol simple.	861	protocol simple.
787		862
788	=item * AEMP has more flexible monitoring options than Erlang.	863	=item * AEMP has more flexible monitoring options than Erlang.
789		864
790	In Erlang, you can chose to receive I<all> exit signals as messages	865	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
793	Erlang, as one can choose between automatic kill, exit message or callback	868	Erlang, as one can choose between automatic kill, exit message or callback
794	on a per-process basis.	869	on a per-process basis.
795		870
796	=item * Erlang tries to hide remote/local connections, AEMP does not.	871	=item * Erlang tries to hide remote/local connections, AEMP does not.
797		872
798	Monitoring in Erlang is not an indicator of process death/crashes,	873	Monitoring in Erlang is not an indicator of process death/crashes, in the
799	as linking is (except linking is unreliable in Erlang).	874	same way as linking is (except linking is unreliable in Erlang).
800		875
801	In AEMP, you don't "look up" registered port names or send to named ports	876	In AEMP, you don't "look up" registered port names or send to named ports
802	that might or might not be persistent. Instead, you normally spawn a port	877	that might or might not be persistent. Instead, you normally spawn a port
803	on the remote node. The init function monitors the you, and you monitor	878	on the remote node. The init function monitors you, and you monitor the
804	the remote port. Since both monitors are local to the node, they are much	879	remote port. Since both monitors are local to the node, they are much more
805	more reliable.	880	reliable (no need for C<spawn_link>).
806		881
807	This also saves round-trips and avoids sending messages to the wrong port	882	This also saves round-trips and avoids sending messages to the wrong port
808	(hard to do in Erlang).	883	(hard to do in Erlang).
809		884
810	=back	885	=back
811		886
812	=head1 RATIONALE	887	=head1 RATIONALE
813		888
814	=over 4	889	=over 4
815		890
816	=item Why strings for ports and noderefs, why not objects?	891	=item Why strings for port and node IDs, why not objects?
817		892
818	We considered "objects", but found that the actual number of methods	893	We considered "objects", but found that the actual number of methods
819	thatc an be called are very low. Since port IDs and noderefs travel over	894	that can be called are quite low. Since port and node IDs travel over
820	the network frequently, the serialising/deserialising would add lots of	895	the network frequently, the serialising/deserialising would add lots of
821	overhead, as well as having to keep a proxy object.	896	overhead, as well as having to keep a proxy object everywhere.
822		897
823	Strings can easily be printed, easily serialised etc. and need no special	898	Strings can easily be printed, easily serialised etc. and need no special
824	procedures to be "valid".	899	procedures to be "valid".
825		900
826	And a a miniport consists of a single closure stored in a global hash - it	901	And as a result, a miniport consists of a single closure stored in a
827	can't become much cheaper.	902	global hash - it can't become much cheaper.
828		903
829	=item Why favour JSON, why not real serialising format such as Storable?	904	=item Why favour JSON, why not a real serialising format such as Storable?
830		905
831	In fact, any AnyEvent::MP node will happily accept Storable as framing	906	In fact, any AnyEvent::MP node will happily accept Storable as framing
832	format, but currently there is no way to make a node use Storable by	907	format, but currently there is no way to make a node use Storable by
833	default.	908	default (although all nodes will accept it).
834		909
835	The default framing protocol is JSON because a) JSON::XS is many times	910	The default framing protocol is JSON because a) JSON::XS is many times
836	faster for small messages and b) most importantly, after years of	911	faster for small messages and b) most importantly, after years of
837	experience we found that object serialisation is causing more problems	912	experience we found that object serialisation is causing more problems
838	than it gains: Just like function calls, objects simply do not travel	913	than it solves: Just like function calls, objects simply do not travel
839	easily over the network, mostly because they will always be a copy, so you	914	easily over the network, mostly because they will always be a copy, so you
840	always have to re-think your design.	915	always have to re-think your design.
841		916
842	Keeping your messages simple, concentrating on data structures rather than	917	Keeping your messages simple, concentrating on data structures rather than
843	objects, will keep your messages clean, tidy and efficient.	918	objects, will keep your messages clean, tidy and efficient.
844		919
845	=back	920	=back
846		921
847	=head1 SEE ALSO	922	=head1 SEE ALSO
848		923
		924	L<AnyEvent::MP::Intro> - a gentle introduction.
		925
		926	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		927
		928	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		929	your applications.
		930
		931	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		932	all nodes.
		933
849	L<AnyEvent>.	934	L<AnyEvent>.
850		935
851	=head1 AUTHOR	936	=head1 AUTHOR
852		937
853	Marc Lehmann <schmorp@schmorp.de>	938	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.57 by root, Sat Aug 15 04:34:34 2009 UTC vs. Revision 1.90 by root, Tue Sep 22 09:38:28 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.57 by root, Sat Aug 15 04:34:34 2009 UTC vs.
Revision 1.90 by root, Tue Sep 22 09:38:28 2009 UTC