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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.62 by root, Thu Aug 27 07:12:48 2009 UTC vs.
Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC

…		…
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
…		…
40	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	38	mon $port, $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46	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.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.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
49		47
50	stay tuned.	48	stay tuned.
51		49
52	=head1 DESCRIPTION	50	=head1 DESCRIPTION
53		51
54	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
55		53
56	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
57	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
58		56
59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60	manual page.	58	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		59
66	=head1 CONCEPTS	60	=head1 CONCEPTS
67		61
68	=over 4	62	=over 4
69		63
70	=item port	64	=item port
71		65
72	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
73		68
74	Ports allow you to register C<rcv> handlers that can match all or just	69	Ports allow you to register C<rcv> handlers that can match all or just
75	some messages. Messages will not be queued.	70	some messages. Messages send to ports will not be queued, regardless of
		71	anything was listening for them or not.
76		72
77	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
78		74
79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as	75	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	76	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		77
84	=item node	78	=item node
85		79
86	A node is a single process containing at least one port - the node port,	80	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	81	which enables nodes to manage each other remotely, and to create new
88	ports.	82	ports.
89		83
90	Nodes are either private (single-process only), slaves (can only talk to	84	Nodes are either public (have one or more listening ports) or private
91	public nodes, but do not need an open port) or public nodes (connectable	85	(no listening ports). Private nodes cannot talk to other private nodes
92	from any other node).	86	currently.
93		87
94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
95		89
96	A node reference is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
97	private and slave nodes), or contains a recipe on how to reach a given	91	network. Depending on the configuration used, node IDs can look like a
98	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
99		94
100	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
101	TCP/IP, other protocols might look different).
102		96
103	Node references come in two flavours: resolved (containing only numerical	97	Nodes can only talk to each other by creating some kind of connection to
104	addresses) or unresolved (where hostnames are used instead of addresses).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
105		101
106	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
107	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Apart from the fact that other nodes know them as seed nodes and they have
		109	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		110	any node can function as a seed node for others.
		111
		112	In addition to discovering the network, seed nodes are also used to
		113	maintain the network and to connect nodes that otherwise would have
		114	trouble connecting. They form the backbone of the AnyEvent::MP network.
		115
		116	Seed nodes are expected to be long-running, and at least one seed node
		117	should always be available. They should also be relatively responsive - a
		118	seed node that blocks for long periods will slow down everybody else.
		119
		120	=item seeds - C<host:port>
		121
		122	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		123	TCP port) of nodes thta should be used as seed nodes.
		124
		125	The nodes listening on those endpoints are expected to be long-running,
		126	and at least one of those should always be available. When nodes run out
		127	of connections (e.g. due to a network error), they try to re-establish
		128	connections to some seednodes again to join the network.
108		129
109	=back	130	=back
110		131
111	=head1 VARIABLES/FUNCTIONS	132	=head1 VARIABLES/FUNCTIONS
112		133
…		…
128		149
129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
130		151
131	our @EXPORT = qw(	152	our @EXPORT = qw(
132	NODE $NODE *SELF node_of after	153	NODE $NODE *SELF node_of after
133	resolve_node initialise_node	154	configure
134	snd rcv mon mon_guard kil reg psub spawn	155	snd rcv mon mon_guard kil reg psub spawn
135	port	156	port
136	);	157	);
137		158
138	our $SELF;	159	our $SELF;
…		…
143	kil $SELF, die => $msg;	164	kil $SELF, die => $msg;
144	}	165	}
145		166
146	=item $thisnode = NODE / $NODE	167	=item $thisnode = NODE / $NODE
147		168
148	The C<NODE> function returns, and the C<$NODE> variable contains the	169	The C<NODE> function returns, and the C<$NODE> variable contains, the node
149	noderef of the local node. The value is initialised by a call to	170	ID of the node running in the current process. This value is initialised by
150	C<initialise_node>.	171	a call to C<configure>.
151		172
152	=item $noderef = node_of $port	173	=item $nodeid = node_of $port
153		174
154	Extracts and returns the noderef from a port ID or a noderef.	175	Extracts and returns the node ID from a port ID or a node ID.
155		176
156	=item initialise_node $noderef, $seednode, $seednode...	177	=item configure $profile, key => value...
157		178
158	=item initialise_node "slave/", $master, $master...	179	=item configure key => value...
159		180
160	Before a node can talk to other nodes on the network it has to initialise	181	Before a node can talk to other nodes on the network (i.e. enter
161	itself - the minimum a node needs to know is it's own name, and optionally	182	"distributed mode") it has to configure itself - the minimum a node needs
162	it should know the noderefs of some other nodes in the network.	183	to know is its own name, and optionally it should know the addresses of
		184	some other nodes in the network to discover other nodes.
163		185
164	This function initialises a node - it must be called exactly once (or	186	This function configures a node - it must be called exactly once (or
165	never) before calling other AnyEvent::MP functions.	187	never) before calling other AnyEvent::MP functions.
166		188
167	All arguments (optionally except for the first) are noderefs, which can be
168	either resolved or unresolved.
169
170	The first argument will be looked up in the configuration database first
171	(if it is C<undef> then the current nodename will be used instead) to find
172	the relevant configuration profile (see L<aemp>). If none is found then
173	the default configuration is used. The configuration supplies additional
174	seed/master nodes and can override the actual noderef.
175
176	There are two types of networked nodes, public nodes and slave nodes:
177
178	=over 4	189	=over 4
179		190
180	=item public nodes	191	=item step 1, gathering configuration from profiles
181		192
182	For public nodes, C<$noderef> (supplied either directly to	193	The function first looks up a profile in the aemp configuration (see the
183	C<initialise_node> or indirectly via a profile or the nodename) must be a	194	L<aemp> commandline utility). The profile name can be specified via the
184	noderef (possibly unresolved, in which case it will be resolved).	195	named C<profile> parameter or can simply be the first parameter). If it is
		196	missing, then the nodename (F<uname -n>) will be used as profile name.
185		197
186	After resolving, the node will bind itself on all endpoints.	198	The profile data is then gathered as follows:
187		199
188	=item slave nodes	200	First, all remaining key => value pairs (all of which are conveniently
		201	undocumented at the moment) will be interpreted as configuration
		202	data. Then they will be overwritten by any values specified in the global
		203	default configuration (see the F<aemp> utility), then the chain of
		204	profiles chosen by the profile name (and any C<parent> attributes).
189		205
190	When the C<$noderef> (either as given or overriden by the config file)	206	That means that the values specified in the profile have highest priority
191	is the special string C<slave/>, then the node will become a slave	207	and the values specified directly via C<configure> have lowest priority,
192	node. Slave nodes cannot be contacted from outside, and cannot talk to	208	and can only be used to specify defaults.
193	each other (at least in this version of AnyEvent::MP).
194		209
195	Slave nodes work by creating connections to all public nodes, using the	210	If the profile specifies a node ID, then this will become the node ID of
196	L<AnyEvent::MP::Global> service.	211	this process. If not, then the profile name will be used as node ID. The
		212	special node ID of C<anon/> will be replaced by a random node ID.
		213
		214	=item step 2, bind listener sockets
		215
		216	The next step is to look up the binds in the profile, followed by binding
		217	aemp protocol listeners on all binds specified (it is possible and valid
		218	to have no binds, meaning that the node cannot be contacted form the
		219	outside. This means the node cannot talk to other nodes that also have no
		220	binds, but it can still talk to all "normal" nodes).
		221
		222	If the profile does not specify a binds list, then a default of C<*> is
		223	used, meaning the node will bind on a dynamically-assigned port on every
		224	local IP address it finds.
		225
		226	=item step 3, connect to seed nodes
		227
		228	As the last step, the seeds list from the profile is passed to the
		229	L<AnyEvent::MP::Global> module, which will then use it to keep
		230	connectivity with at least one node at any point in time.
197		231
198	=back	232	=back
199		233
200	After initialising itself, the node will connect to all additional	234	Example: become a distributed node using the locla node name as profile.
201	C<$seednodes> that are specified diretcly or via a profile. Seednodes are	235	This should be the most common form of invocation for "daemon"-type nodes.
202	optional and can be used to quickly bootstrap the node into an existing
203	network.
204		236
205	All the seednodes will also be specially marked to automatically retry	237	configure
206	connecting to them indefinitely, so make sure that seednodes are really
207	reliable and up (this might also change in the future).
208		238
209	Example: become a public node listening on the guessed noderef, or the one	239	Example: become an anonymous node. This form is often used for commandline
210	specified via C<aemp> for the current node. This should be the most common	240	clients.
211	form of invocation for "daemon"-type nodes.
212		241
213	initialise_node;	242	configure nodeid => "anon/";
214		243
215	Example: become a slave node to any of the the seednodes specified via	244	Example: configure a node using a profile called seed, which si suitable
216	C<aemp>. This form is often used for commandline clients.	245	for a seed node as it binds on all local addresses on a fixed port (4040,
		246	customary for aemp).
217		247
218	initialise_node "slave/";	248	# use the aemp commandline utility
		249	# aemp profile seed nodeid anon/ binds '*:4040'
219		250
220	Example: become a public node, and try to contact some well-known master	251	# then use it
221	servers to become part of the network.	252	configure profile => "seed";
222		253
223	initialise_node undef, "master1", "master2";	254	# or simply use aemp from the shell again:
		255	# aemp run profile seed
224		256
225	Example: become a public node listening on port C<4041>.	257	# or provide a nicer-to-remember nodeid
226		258	# aemp run profile seed nodeid "$(hostname)"
227	initialise_node 4041;
228
229	Example: become a public node, only visible on localhost port 4044.
230
231	initialise_node "localhost:4044";
232
233	=item $cv = resolve_node $noderef
234
235	Takes an unresolved node reference that may contain hostnames and
236	abbreviated IDs, resolves all of them and returns a resolved node
237	reference.
238
239	In addition to C<address:port> pairs allowed in resolved noderefs, the
240	following forms are supported:
241
242	=over 4
243
244	=item the empty string
245
246	An empty-string component gets resolved as if the default port (4040) was
247	specified.
248
249	=item naked port numbers (e.g. C<1234>)
250
251	These are resolved by prepending the local nodename and a colon, to be
252	further resolved.
253
254	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
255
256	These are resolved by using AnyEvent::DNS to resolve them, optionally
257	looking up SRV records for the C<aemp=4040> port, if no port was
258	specified.
259
260	=back
261		259
262	=item $SELF	260	=item $SELF
263		261
264	Contains the current port id while executing C<rcv> callbacks or C<psub>	262	Contains the current port id while executing C<rcv> callbacks or C<psub>
265	blocks.	263	blocks.
266		264
267	=item SELF, %SELF, @SELF...	265	=item *SELF, SELF, %SELF, @SELF...
268		266
269	Due to some quirks in how perl exports variables, it is impossible to	267	Due to some quirks in how perl exports variables, it is impossible to
270	just export C<$SELF>, all the symbols called C<SELF> are exported by this	268	just export C<$SELF>, all the symbols named C<SELF> are exported by this
271	module, but only C<$SELF> is currently used.	269	module, but only C<$SELF> is currently used.
272		270
273	=item snd $port, type => @data	271	=item snd $port, type => @data
274		272
275	=item snd $port, @msg	273	=item snd $port, @msg
276		274
277	Send the given message to the given port ID, which can identify either	275	Send the given message to the given port, which can identify either a
278	a local or a remote port, and must be a port ID.	276	local or a remote port, and must be a port ID.
279		277
280	While the message can be about anything, it is highly recommended to use a	278	While the message can be almost anything, it is highly recommended to
281	string as first element (a port ID, or some word that indicates a request	279	use a string as first element (a port ID, or some word that indicates a
282	type etc.).	280	request type etc.) and to consist if only simple perl values (scalars,
		281	arrays, hashes) - if you think you need to pass an object, think again.
283		282
284	The message data effectively becomes read-only after a call to this	283	The message data logically becomes read-only after a call to this
285	function: modifying any argument is not allowed and can cause many	284	function: modifying any argument (or values referenced by them) is
286	problems.	285	forbidden, as there can be considerable time between the call to C<snd>
		286	and the time the message is actually being serialised - in fact, it might
		287	never be copied as within the same process it is simply handed to the
		288	receiving port.
287		289
288	The type of data you can transfer depends on the transport protocol: when	290	The type of data you can transfer depends on the transport protocol: when
289	JSON is used, then only strings, numbers and arrays and hashes consisting	291	JSON is used, then only strings, numbers and arrays and hashes consisting
290	of those are allowed (no objects). When Storable is used, then anything	292	of those are allowed (no objects). When Storable is used, then anything
291	that Storable can serialise and deserialise is allowed, and for the local	293	that Storable can serialise and deserialise is allowed, and for the local
292	node, anything can be passed.	294	node, anything can be passed. Best rely only on the common denominator of
		295	these.
293		296
294	=item $local_port = port	297	=item $local_port = port
295		298
296	Create a new local port object and returns its port ID. Initially it has	299	Create a new local port object and returns its port ID. Initially it has
297	no callbacks set and will throw an error when it receives messages.	300	no callbacks set and will throw an error when it receives messages.
…		…
382		385
383	=cut	386	=cut
384		387
385	sub rcv($@) {	388	sub rcv($@) {
386	my $port = shift;	389	my $port = shift;
387	my ($noderef, $portid) = split /#/, $port, 2;	390	my ($nodeid, $portid) = split /#/, $port, 2;
388		391
389	$NODE{$noderef} == $NODE{""}	392	$NODE{$nodeid} == $NODE{""}
390	or Carp::croak "$port: rcv can only be called on local ports, caught";	393	or Carp::croak "$port: rcv can only be called on local ports, caught";
391		394
392	while (@_) {	395	while (@_) {
393	if (ref $_[0]) {	396	if (ref $_[0]) {
394	if (my $self = $PORT_DATA{$portid}) {	397	if (my $self = $PORT_DATA{$portid}) {
…		…
473	$res	476	$res
474	}	477	}
475	}	478	}
476	}	479	}
477		480
478	=item $guard = mon $port, $cb->(@reason)	481	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
479		482
480	=item $guard = mon $port, $rcvport	483	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
481		484
482	=item $guard = mon $port	485	=item $guard = mon $port # kill $SELF when $port dies
483		486
484	=item $guard = mon $port, $rcvport, @msg	487	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
485		488
486	Monitor the given port and do something when the port is killed or	489	Monitor the given port and do something when the port is killed or
487	messages to it were lost, and optionally return a guard that can be used	490	messages to it were lost, and optionally return a guard that can be used
488	to stop monitoring again.	491	to stop monitoring again.
489
490	C<mon> effectively guarantees that, in the absence of hardware failures,
491	that after starting the monitor, either all messages sent to the port
492	will arrive, or the monitoring action will be invoked after possible
493	message loss has been detected. No messages will be lost "in between"
494	(after the first lost message no further messages will be received by the
495	port). After the monitoring action was invoked, further messages might get
496	delivered again.
497
498	Note that monitoring-actions are one-shot: once released, they are removed
499	and will not trigger again.
500		492
501	In the first form (callback), the callback is simply called with any	493	In the first form (callback), the callback is simply called with any
502	number of C<@reason> elements (no @reason means that the port was deleted	494	number of C<@reason> elements (no @reason means that the port was deleted
503	"normally"). Note also that I<< the callback B<must> never die >>, so use	495	"normally"). Note also that I<< the callback B<must> never die >>, so use
504	C<eval> if unsure.	496	C<eval> if unsure.
505		497
506	In the second form (another port given), the other port (C<$rcvport>)	498	In the second form (another port given), the other port (C<$rcvport>)
507	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	499	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
508	"normal" kils nothing happens, while under all other conditions, the other	500	"normal" kils nothing happens, while under all other conditions, the other
509	port is killed with the same reason.	501	port is killed with the same reason.
510		502
511	The third form (kill self) is the same as the second form, except that	503	The third form (kill self) is the same as the second form, except that
512	C<$rvport> defaults to C<$SELF>.	504	C<$rvport> defaults to C<$SELF>.
513		505
514	In the last form (message), a message of the form C<@msg, @reason> will be	506	In the last form (message), a message of the form C<@msg, @reason> will be
515	C<snd>.	507	C<snd>.
		508
		509	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		510	alert was raised), they are removed and will not trigger again.
516		511
517	As a rule of thumb, monitoring requests should always monitor a port from	512	As a rule of thumb, monitoring requests should always monitor a port from
518	a local port (or callback). The reason is that kill messages might get	513	a local port (or callback). The reason is that kill messages might get
519	lost, just like any other message. Another less obvious reason is that	514	lost, just like any other message. Another less obvious reason is that
520	even monitoring requests can get lost (for exmaple, when the connection	515	even monitoring requests can get lost (for example, when the connection
521	to the other node goes down permanently). When monitoring a port locally	516	to the other node goes down permanently). When monitoring a port locally
522	these problems do not exist.	517	these problems do not exist.
523		518
		519	C<mon> effectively guarantees that, in the absence of hardware failures,
		520	after starting the monitor, either all messages sent to the port will
		521	arrive, or the monitoring action will be invoked after possible message
		522	loss has been detected. No messages will be lost "in between" (after
		523	the first lost message no further messages will be received by the
		524	port). After the monitoring action was invoked, further messages might get
		525	delivered again.
		526
		527	Inter-host-connection timeouts and monitoring depend on the transport
		528	used. The only transport currently implemented is TCP, and AnyEvent::MP
		529	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		530	non-idle connection, and usually around two hours for idle conenctions).
		531
		532	This means that monitoring is good for program errors and cleaning up
		533	stuff eventually, but they are no replacement for a timeout when you need
		534	to ensure some maximum latency.
		535
524	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
525		537
526	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
527		539
528	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
…		…
534	mon $port, $self => "restart";	546	mon $port, $self => "restart";
535		547
536	=cut	548	=cut
537		549
538	sub mon {	550	sub mon {
539	my ($noderef, $port) = split /#/, shift, 2;	551	my ($nodeid, $port) = split /#/, shift, 2;
540		552
541	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
542		554
543	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
544		556
545	unless (ref $cb) {	557	unless (ref $cb) {
546	if (@_) {	558	if (@_) {
…		…
566	is killed, the references will be freed.	578	is killed, the references will be freed.
567		579
568	Optionally returns a guard that will stop the monitoring.	580	Optionally returns a guard that will stop the monitoring.
569		581
570	This function is useful when you create e.g. timers or other watchers and	582	This function is useful when you create e.g. timers or other watchers and
571	want to free them when the port gets killed:	583	want to free them when the port gets killed (note the use of C<psub>):
572		584
573	$port->rcv (start => sub {	585	$port->rcv (start => sub {
574	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	586	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
575	undef $timer if 0.9 < rand;	587	undef $timer if 0.9 < rand;
576	});	588	});
577	});	589	});
578		590
579	=cut	591	=cut
…		…
588		600
589	=item kil $port[, @reason]	601	=item kil $port[, @reason]
590		602
591	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
592		604
593	If no C<@reason> is specified, then the port is killed "normally" (linked	605	If no C<@reason> is specified, then the port is killed "normally" (ports
594	ports will not be kileld, or even notified).	606	monitoring other ports will not necessarily die because a port dies
		607	"normally").
595		608
596	Otherwise, linked ports get killed with the same reason (second form of	609	Otherwise, linked ports get killed with the same reason (second form of
597	C<mon>, see below).	610	C<mon>, see above).
598		611
599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	612	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
600	will be reported as reason C<< die => $@ >>.	613	will be reported as reason C<< die => $@ >>.
601		614
602	Transport/communication errors are reported as C<< transport_error =>	615	Transport/communication errors are reported as C<< transport_error =>
…		…
607	=item $port = spawn $node, $initfunc[, @initdata]	620	=item $port = spawn $node, $initfunc[, @initdata]
608		621
609	Creates a port on the node C<$node> (which can also be a port ID, in which	622	Creates a port on the node C<$node> (which can also be a port ID, in which
610	case it's the node where that port resides).	623	case it's the node where that port resides).
611		624
612	The port ID of the newly created port is return immediately, and it is	625	The port ID of the newly created port is returned immediately, and it is
613	permissible to immediately start sending messages or monitor the port.	626	possible to immediately start sending messages or to monitor the port.
614		627
615	After the port has been created, the init function is	628	After the port has been created, the init function is called on the remote
616	called. This function must be a fully-qualified function name	629	node, in the same context as a C<rcv> callback. This function must be a
617	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	630	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
618	program, use C<::name>.	631	specify a function in the main program, use C<::name>.
619		632
620	If the function doesn't exist, then the node tries to C<require>	633	If the function doesn't exist, then the node tries to C<require>
621	the package, then the package above the package and so on (e.g.	634	the package, then the package above the package and so on (e.g.
622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	635	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
623	exists or it runs out of package names.	636	exists or it runs out of package names.
624		637
625	The init function is then called with the newly-created port as context	638	The init function is then called with the newly-created port as context
626	object (C<$SELF>) and the C<@initdata> values as arguments.	639	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		640	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		641	the port might not get created.
627		642
628	A common idiom is to pass your own port, monitor the spawned port, and	643	A common idiom is to pass a local port, immediately monitor the spawned
629	in the init function, monitor the original port. This two-way monitoring	644	port, and in the remote init function, immediately monitor the passed
630	ensures that both ports get cleaned up when there is a problem.	645	local port. This two-way monitoring ensures that both ports get cleaned up
		646	when there is a problem.
		647
		648	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		649	caller before C<spawn> returns (by delaying invocation when spawn is
		650	called for the local node).
631		651
632	Example: spawn a chat server port on C<$othernode>.	652	Example: spawn a chat server port on C<$othernode>.
633		653
634	# this node, executed from within a port context:	654	# this node, executed from within a port context:
635	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	655	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
650		670
651	sub _spawn {	671	sub _spawn {
652	my $port = shift;	672	my $port = shift;
653	my $init = shift;	673	my $init = shift;
654		674
		675	# rcv will create the actual port
655	local $SELF = "$NODE#$port";	676	local $SELF = "$NODE#$port";
656	eval {	677	eval {
657	&{ load_func $init }	678	&{ load_func $init }
658	};	679	};
659	_self_die if $@;	680	_self_die if $@;
660	}	681	}
661		682
662	sub spawn(@) {	683	sub spawn(@) {
663	my ($noderef, undef) = split /#/, shift, 2;	684	my ($nodeid, undef) = split /#/, shift, 2;
664		685
665	my $id = "$RUNIQ." . $ID++;	686	my $id = "$RUNIQ." . $ID++;
666		687
667	$_[0] =~ /::/	688	$_[0] =~ /::/
668	or Carp::croak "spawn init function must be a fully-qualified name, caught";	689	or Carp::croak "spawn init function must be a fully-qualified name, caught";
669		690
670	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
671		692
672	"$noderef#$id"	693	"$nodeid#$id"
673	}	694	}
674		695
675	=item after $timeout, @msg	696	=item after $timeout, @msg
676		697
677	=item after $timeout, $callback	698	=item after $timeout, $callback
678		699
679	Either sends the given message, or call the given callback, after the	700	Either sends the given message, or call the given callback, after the
680	specified number of seconds.	701	specified number of seconds.
681		702
682	This is simply a utility function that come sin handy at times.	703	This is simply a utility function that comes in handy at times - the
		704	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		705	so it may go away in the future.
683		706
684	=cut	707	=cut
685		708
686	sub after($@) {	709	sub after($@) {
687	my ($timeout, @action) = @_;	710	my ($timeout, @action) = @_;
…		…
710		733
711	Despite the similarities, there are also some important differences:	734	Despite the similarities, there are also some important differences:
712		735
713	=over 4	736	=over 4
714		737
715	=item * Node references contain the recipe on how to contact them.	738	=item * Node IDs are arbitrary strings in AEMP.
716		739
717	Erlang relies on special naming and DNS to work everywhere in the	740	Erlang relies on special naming and DNS to work everywhere in the same
718	same way. AEMP relies on each node knowing it's own address(es), with	741	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
719	convenience functionality.	742	configuration or DNS), but will otherwise discover other odes itself.
720
721	This means that AEMP requires a less tightly controlled environment at the
722	cost of longer node references and a slightly higher management overhead.
723		743
724	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	744	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
725	uses "local ports are like remote ports".	745	uses "local ports are like remote ports".
726		746
727	The failure modes for local ports are quite different (runtime errors	747	The failure modes for local ports are quite different (runtime errors
…		…
740		760
741	Erlang uses processes that selectively receive messages, and therefore	761	Erlang uses processes that selectively receive messages, and therefore
742	needs a queue. AEMP is event based, queuing messages would serve no	762	needs a queue. AEMP is event based, queuing messages would serve no
743	useful purpose. For the same reason the pattern-matching abilities of	763	useful purpose. For the same reason the pattern-matching abilities of
744	AnyEvent::MP are more limited, as there is little need to be able to	764	AnyEvent::MP are more limited, as there is little need to be able to
745	filter messages without dequeing them.	765	filter messages without dequeuing them.
746		766
747	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	767	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
748		768
749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
750		770
…		…
756		776
757	Erlang makes few guarantees on messages delivery - messages can get lost	777	Erlang makes few guarantees on messages delivery - messages can get lost
758	without any of the processes realising it (i.e. you send messages a, b,	778	without any of the processes realising it (i.e. you send messages a, b,
759	and c, and the other side only receives messages a and c).	779	and c, and the other side only receives messages a and c).
760		780
761	AEMP guarantees correct ordering, and the guarantee that there are no	781	AEMP guarantees correct ordering, and the guarantee that after one message
762	holes in the message sequence.	782	is lost, all following ones sent to the same port are lost as well, until
763		783	monitoring raises an error, so there are no silent "holes" in the message
764	=item * In Erlang, processes can be declared dead and later be found to be	784	sequence.
765	alive.
766
767	In Erlang it can happen that a monitored process is declared dead and
768	linked processes get killed, but later it turns out that the process is
769	still alive - and can receive messages.
770
771	In AEMP, when port monitoring detects a port as dead, then that port will
772	eventually be killed - it cannot happen that a node detects a port as dead
773	and then later sends messages to it, finding it is still alive.
774		785
775	=item * Erlang can send messages to the wrong port, AEMP does not.	786	=item * Erlang can send messages to the wrong port, AEMP does not.
776		787
777	In Erlang it is quite likely that a node that restarts reuses a process ID	788	In Erlang it is quite likely that a node that restarts reuses a process ID
778	known to other nodes for a completely different process, causing messages	789	known to other nodes for a completely different process, causing messages
…		…
782	around in the network will not be sent to an unrelated port.	793	around in the network will not be sent to an unrelated port.
783		794
784	=item * Erlang uses unprotected connections, AEMP uses secure	795	=item * Erlang uses unprotected connections, AEMP uses secure
785	authentication and can use TLS.	796	authentication and can use TLS.
786		797
787	AEMP can use a proven protocol - SSL/TLS - to protect connections and	798	AEMP can use a proven protocol - TLS - to protect connections and
788	securely authenticate nodes.	799	securely authenticate nodes.
789		800
790	=item * The AEMP protocol is optimised for both text-based and binary	801	=item * The AEMP protocol is optimised for both text-based and binary
791	communications.	802	communications.
792		803
793	The AEMP protocol, unlike the Erlang protocol, supports both	804	The AEMP protocol, unlike the Erlang protocol, supports both programming
794	language-independent text-only protocols (good for debugging) and binary,	805	language independent text-only protocols (good for debugging) and binary,
795	language-specific serialisers (e.g. Storable).	806	language-specific serialisers (e.g. Storable). By default, unless TLS is
		807	used, the protocol is actually completely text-based.
796		808
797	It has also been carefully designed to be implementable in other languages	809	It has also been carefully designed to be implementable in other languages
798	with a minimum of work while gracefully degrading fucntionality to make the	810	with a minimum of work while gracefully degrading functionality to make the
799	protocol simple.	811	protocol simple.
800		812
801	=item * AEMP has more flexible monitoring options than Erlang.	813	=item * AEMP has more flexible monitoring options than Erlang.
802		814
803	In Erlang, you can chose to receive I<all> exit signals as messages	815	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
806	Erlang, as one can choose between automatic kill, exit message or callback	818	Erlang, as one can choose between automatic kill, exit message or callback
807	on a per-process basis.	819	on a per-process basis.
808		820
809	=item * Erlang tries to hide remote/local connections, AEMP does not.	821	=item * Erlang tries to hide remote/local connections, AEMP does not.
810		822
811	Monitoring in Erlang is not an indicator of process death/crashes,	823	Monitoring in Erlang is not an indicator of process death/crashes, in the
812	as linking is (except linking is unreliable in Erlang).	824	same way as linking is (except linking is unreliable in Erlang).
813		825
814	In AEMP, you don't "look up" registered port names or send to named ports	826	In AEMP, you don't "look up" registered port names or send to named ports
815	that might or might not be persistent. Instead, you normally spawn a port	827	that might or might not be persistent. Instead, you normally spawn a port
816	on the remote node. The init function monitors the you, and you monitor	828	on the remote node. The init function monitors you, and you monitor the
817	the remote port. Since both monitors are local to the node, they are much	829	remote port. Since both monitors are local to the node, they are much more
818	more reliable.	830	reliable (no need for C<spawn_link>).
819		831
820	This also saves round-trips and avoids sending messages to the wrong port	832	This also saves round-trips and avoids sending messages to the wrong port
821	(hard to do in Erlang).	833	(hard to do in Erlang).
822		834
823	=back	835	=back
824		836
825	=head1 RATIONALE	837	=head1 RATIONALE
826		838
827	=over 4	839	=over 4
828		840
829	=item Why strings for ports and noderefs, why not objects?	841	=item Why strings for port and node IDs, why not objects?
830		842
831	We considered "objects", but found that the actual number of methods	843	We considered "objects", but found that the actual number of methods
832	thatc an be called are very low. Since port IDs and noderefs travel over	844	that can be called are quite low. Since port and node IDs travel over
833	the network frequently, the serialising/deserialising would add lots of	845	the network frequently, the serialising/deserialising would add lots of
834	overhead, as well as having to keep a proxy object.	846	overhead, as well as having to keep a proxy object everywhere.
835		847
836	Strings can easily be printed, easily serialised etc. and need no special	848	Strings can easily be printed, easily serialised etc. and need no special
837	procedures to be "valid".	849	procedures to be "valid".
838		850
839	And a a miniport consists of a single closure stored in a global hash - it	851	And as a result, a miniport consists of a single closure stored in a
840	can't become much cheaper.	852	global hash - it can't become much cheaper.
841		853
842	=item Why favour JSON, why not real serialising format such as Storable?	854	=item Why favour JSON, why not a real serialising format such as Storable?
843		855
844	In fact, any AnyEvent::MP node will happily accept Storable as framing	856	In fact, any AnyEvent::MP node will happily accept Storable as framing
845	format, but currently there is no way to make a node use Storable by	857	format, but currently there is no way to make a node use Storable by
846	default.	858	default (although all nodes will accept it).
847		859
848	The default framing protocol is JSON because a) JSON::XS is many times	860	The default framing protocol is JSON because a) JSON::XS is many times
849	faster for small messages and b) most importantly, after years of	861	faster for small messages and b) most importantly, after years of
850	experience we found that object serialisation is causing more problems	862	experience we found that object serialisation is causing more problems
851	than it gains: Just like function calls, objects simply do not travel	863	than it solves: Just like function calls, objects simply do not travel
852	easily over the network, mostly because they will always be a copy, so you	864	easily over the network, mostly because they will always be a copy, so you
853	always have to re-think your design.	865	always have to re-think your design.
854		866
855	Keeping your messages simple, concentrating on data structures rather than	867	Keeping your messages simple, concentrating on data structures rather than
856	objects, will keep your messages clean, tidy and efficient.	868	objects, will keep your messages clean, tidy and efficient.
857		869
858	=back	870	=back
859		871
860	=head1 SEE ALSO	872	=head1 SEE ALSO
861		873
		874	L<AnyEvent::MP::Intro> - a gentle introduction.
		875
		876	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		877
		878	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		879	your applications.
		880
		881	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		882	all nodes.
		883
862	L<AnyEvent>.	884	L<AnyEvent>.
863		885
864	=head1 AUTHOR	886	=head1 AUTHOR
865		887
866	Marc Lehmann <schmorp@schmorp.de>	888	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.62 by root, Thu Aug 27 07:12:48 2009 UTC vs. Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.62 by root, Thu Aug 27 07:12:48 2009 UTC vs.
Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC