[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 1.88 by root, Fri Sep 11 15:02:17 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46	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.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 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 (can only talk to	82	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	83	(no listening ports). Private nodes cannot talk to other private nodes
92	from any other node).	84	currently.
93		85
94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
95		87
96	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
97	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
98	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.
99		92
100	This recipe is simply a comma-separated list of C<address:port> pairs (for	93	=item binds - C<ip:port>
101	TCP/IP, other protocols might look different).
102		94
103	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
104	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.
105		99
106	Before using an unresolved node reference in a message you first have to	100	=item seed nodes
107	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.
108		127
109	=back	128	=back
110		129
111	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
112		131
…		…
128		147
129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	148	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
130		149
131	our @EXPORT = qw(	150	our @EXPORT = qw(
132	NODE $NODE *SELF node_of after	151	NODE $NODE *SELF node_of after
133	resolve_node initialise_node	152	configure
134	snd rcv mon mon_guard kil reg psub spawn	153	snd rcv mon mon_guard kil reg psub spawn cal
135	port	154	port
136	);	155	);
137		156
138	our $SELF;	157	our $SELF;
139		158
…		…
143	kil $SELF, die => $msg;	162	kil $SELF, die => $msg;
144	}	163	}
145		164
146	=item $thisnode = NODE / $NODE	165	=item $thisnode = NODE / $NODE
147		166
148	The C<NODE> function returns, and the C<$NODE> variable contains the	167	The C<NODE> function returns, and the C<$NODE> variable contains, the node
149	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
150	C<initialise_node>.	169	a call to C<configure>.
151		170
152	=item $noderef = node_of $port	171	=item $nodeid = node_of $port
153		172
154	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.
155		174
156	=item initialise_node $noderef, $seednode, $seednode...	175	=item configure $profile, key => value...
157		176
158	=item initialise_node "slave/", $master, $master...	177	=item configure key => value...
159		178
160	Before a node can talk to other nodes on the network it has to initialise	179	Before a node can talk to other nodes on the network (i.e. enter
161	itself - the minimum a node needs to know is it's own name, and optionally	180	"distributed mode") it has to configure itself - the minimum a node needs
162	it should know the noderefs of some other nodes in the network.	181	to know is its own name, and optionally it should know the addresses of
		182	some other nodes in the network to discover other nodes.
163		183
164	This function initialises a node - it must be called exactly once (or	184	This function configures a node - it must be called exactly once (or
165	never) before calling other AnyEvent::MP functions.	185	never) before calling other AnyEvent::MP functions.
166		186
167	All arguments (optionally except for the first) are noderefs, which can be
168	either resolved or unresolved.
169
170	The first argument will be looked up in the configuration database first
171	(if it is C<undef> then the current nodename will be used instead) to find
172	the relevant configuration profile (see L<aemp>). If none is found then
173	the default configuration is used. The configuration supplies additional
174	seed/master nodes and can override the actual noderef.
175
176	There are two types of networked nodes, public nodes and slave nodes:
177
178	=over 4	187	=over 4
179		188
180	=item public nodes	189	=item step 1, gathering configuration from profiles
181		190
182	For public nodes, C<$noderef> (supplied either directly to	191	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	192	L<aemp> commandline utility). The profile name can be specified via the
184	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.
185		195
186	After resolving, the node will bind itself on all endpoints.	196	The profile data is then gathered as follows:
187		197
188	=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).
189		203
190	When the C<$noderef> (either as given or overriden by the config file)	204	That means that the values specified in the profile have highest priority
191	is the special string C<slave/>, then the node will become a slave	205	and the values specified directly via C<configure> have lowest priority,
192	node. Slave nodes cannot be contacted from outside, and cannot talk to	206	and can only be used to specify defaults.
193	each other (at least in this version of AnyEvent::MP).
194		207
195	Slave nodes work by creating connections to all public nodes, using the	208	If the profile specifies a node ID, then this will become the node ID of
196	L<AnyEvent::MP::Global> service.	209	this process. If not, then the profile name will be used as node ID. The
		210	special node ID of C<anon/> will be replaced by a random node ID.
		211
		212	=item step 2, bind listener sockets
		213
		214	The next step is to look up the binds in the profile, followed by binding
		215	aemp protocol listeners on all binds specified (it is possible and valid
		216	to have no binds, meaning that the node cannot be contacted form the
		217	outside. This means the node cannot talk to other nodes that also have no
		218	binds, but it can still talk to all "normal" nodes).
		219
		220	If the profile does not specify a binds list, then a default of C<*> is
		221	used, meaning the node will bind on a dynamically-assigned port on every
		222	local IP address it finds.
		223
		224	=item step 3, connect to seed nodes
		225
		226	As the last step, the seeds list from the profile is passed to the
		227	L<AnyEvent::MP::Global> module, which will then use it to keep
		228	connectivity with at least one node at any point in time.
197		229
198	=back	230	=back
199		231
200	After initialising itself, the node will connect to all additional	232	Example: become a distributed node using the local node name as profile.
201	C<$seednodes> that are specified diretcly or via a profile. Seednodes are	233	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		234
205	All the seednodes will also be specially marked to automatically retry	235	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		236
209	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
210	specified via C<aemp> for the current node. This should be the most common	238	clients.
211	form of invocation for "daemon"-type nodes.
212		239
213	initialise_node;	240	configure nodeid => "anon/";
214		241
215	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
216	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).
217		245
218	initialise_node "slave/";	246	# use the aemp commandline utility
		247	# aemp profile seed nodeid anon/ binds '*:4040'
219		248
220	Example: become a public node, and try to contact some well-known master	249	# then use it
221	servers to become part of the network.	250	configure profile => "seed";
222		251
223	initialise_node undef, "master1", "master2";	252	# or simply use aemp from the shell again:
		253	# aemp run profile seed
224		254
225	Example: become a public node listening on port C<4041>.	255	# or provide a nicer-to-remember nodeid
226		256	# 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		257
262	=item $SELF	258	=item $SELF
263		259
264	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
265	blocks.	261	blocks.
266		262
267	=item SELF, %SELF, @SELF...	263	=item *SELF, SELF, %SELF, @SELF...
268		264
269	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
270	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols named C<SELF> are exported by this
271	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
272		268
273	=item snd $port, type => @data	269	=item snd $port, type => @data
274		270
275	=item snd $port, @msg	271	=item snd $port, @msg
276		272
277	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
278	a local or a remote port, and must be a port ID.	274	local or a remote port, and must be a port ID.
279		275
280	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
281	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
282	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.
283		280
284	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
285	function: modifying any argument is not allowed and can cause many	282	function: modifying any argument (or values referenced by them) is
286	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.
287		287
288	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
289	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
290	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
291	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
292	node, anything can be passed.	292	node, anything can be passed. Best rely only on the common denominator of
		293	these.
293		294
294	=item $local_port = port	295	=item $local_port = port
295		296
296	Create a new local port object and returns its port ID. Initially it has	297	Create a new local port object and returns its port ID. Initially it has
297	no callbacks set and will throw an error when it receives messages.	298	no callbacks set and will throw an error when it receives messages.
…		…
382		383
383	=cut	384	=cut
384		385
385	sub rcv($@) {	386	sub rcv($@) {
386	my $port = shift;	387	my $port = shift;
387	my ($noderef, $portid) = split /#/, $port, 2;	388	my ($nodeid, $portid) = split /#/, $port, 2;
388		389
389	$NODE{$noderef} == $NODE{""}	390	$NODE{$nodeid} == $NODE{""}
390	or Carp::croak "$port: rcv can only be called on local ports, caught";	391	or Carp::croak "$port: rcv can only be called on local ports, caught";
391		392
392	while (@_) {	393	while (@_) {
393	if (ref $_[0]) {	394	if (ref $_[0]) {
394	if (my $self = $PORT_DATA{$portid}) {	395	if (my $self = $PORT_DATA{$portid}) {
…		…
473	$res	474	$res
474	}	475	}
475	}	476	}
476	}	477	}
477		478
478	=item $guard = mon $port, $cb->(@reason)	479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
479		480
480	=item $guard = mon $port, $rcvport	481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
481		482
482	=item $guard = mon $port	483	=item $guard = mon $port # kill $SELF when $port dies
483		484
484	=item $guard = mon $port, $rcvport, @msg	485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
485		486
486	Monitor the given port and do something when the port is killed or	487	Monitor the given port and do something when the port is killed or
487	messages to it were lost, and optionally return a guard that can be used	488	messages to it were lost, and optionally return a guard that can be used
488	to stop monitoring again.	489	to stop monitoring again.
489
490	C<mon> effectively guarantees that, in the absence of hardware failures,
491	that after starting the monitor, either all messages sent to the port
492	will arrive, or the monitoring action will be invoked after possible
493	message loss has been detected. No messages will be lost "in between"
494	(after the first lost message no further messages will be received by the
495	port). After the monitoring action was invoked, further messages might get
496	delivered again.
497
498	Note that monitoring-actions are one-shot: once released, they are removed
499	and will not trigger again.
500		490
501	In the first form (callback), the callback is simply called with any	491	In the first form (callback), the callback is simply called with any
502	number of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
503	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
504	C<eval> if unsure.	494	C<eval> if unsure.
505		495
506	In the second form (another port given), the other port (C<$rcvport>)	496	In the second form (another port given), the other port (C<$rcvport>)
507	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
508	"normal" kils nothing happens, while under all other conditions, the other	498	"normal" kils nothing happens, while under all other conditions, the other
509	port is killed with the same reason.	499	port is killed with the same reason.
510		500
511	The third form (kill self) is the same as the second form, except that	501	The third form (kill self) is the same as the second form, except that
512	C<$rvport> defaults to C<$SELF>.	502	C<$rvport> defaults to C<$SELF>.
513		503
514	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
515	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.
516		509
517	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
518	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
519	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
520	even monitoring requests can get lost (for exmaple, when the connection	513	even monitoring requests can get lost (for example, when the connection
521	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
522	these problems do not exist.	515	these problems do not exist.
523		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
524	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
525		535
526	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
527		537
528	Example: kill ourselves when C<$port> is killed abnormally.	538	Example: kill ourselves when C<$port> is killed abnormally.
…		…
534	mon $port, $self => "restart";	544	mon $port, $self => "restart";
535		545
536	=cut	546	=cut
537		547
538	sub mon {	548	sub mon {
539	my ($noderef, $port) = split /#/, shift, 2;	549	my ($nodeid, $port) = split /#/, shift, 2;
540		550
541	my $node = $NODE{$noderef} \|\| add_node $noderef;	551	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
542		552
543	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,';
544		554
545	unless (ref $cb) {	555	unless (ref $cb) {
546	if (@_) {	556	if (@_) {
…		…
566	is killed, the references will be freed.	576	is killed, the references will be freed.
567		577
568	Optionally returns a guard that will stop the monitoring.	578	Optionally returns a guard that will stop the monitoring.
569		579
570	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
571	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>):
572		582
573	$port->rcv (start => sub {	583	$port->rcv (start => sub {
574	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	584	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
575	undef $timer if 0.9 < rand;	585	undef $timer if 0.9 < rand;
576	});	586	});
577	});	587	});
578		588
579	=cut	589	=cut
…		…
588		598
589	=item kil $port[, @reason]	599	=item kil $port[, @reason]
590		600
591	Kill the specified port with the given C<@reason>.	601	Kill the specified port with the given C<@reason>.
592		602
593	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
594	ports will not be kileld, or even notified).	604	monitoring other ports will not necessarily die because a port dies
		605	"normally").
595		606
596	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
597	C<mon>, see below).	608	C<mon>, see above).
598		609
599	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
600	will be reported as reason C<< die => $@ >>.	611	will be reported as reason C<< die => $@ >>.
601		612
602	Transport/communication errors are reported as C<< transport_error =>	613	Transport/communication errors are reported as C<< transport_error =>
…		…
607	=item $port = spawn $node, $initfunc[, @initdata]	618	=item $port = spawn $node, $initfunc[, @initdata]
608		619
609	Creates a port on the node C<$node> (which can also be a port ID, in which	620	Creates a port on the node C<$node> (which can also be a port ID, in which
610	case it's the node where that port resides).	621	case it's the node where that port resides).
611		622
612	The port ID of the newly created port is return immediately, and it is	623	The port ID of the newly created port is returned immediately, and it is
613	permissible to immediately start sending messages or monitor the port.	624	possible to immediately start sending messages or to monitor the port.
614		625
615	After the port has been created, the init function is	626	After the port has been created, the init function is called on the remote
616	called. This function must be a fully-qualified function name	627	node, in the same context as a C<rcv> callback. This function must be a
617	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	628	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
618	program, use C<::name>.	629	specify a function in the main program, use C<::name>.
619		630
620	If the function doesn't exist, then the node tries to C<require>	631	If the function doesn't exist, then the node tries to C<require>
621	the package, then the package above the package and so on (e.g.	632	the package, then the package above the package and so on (e.g.
622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	633	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
623	exists or it runs out of package names.	634	exists or it runs out of package names.
624		635
625	The init function is then called with the newly-created port as context	636	The init function is then called with the newly-created port as context
626	object (C<$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.
627		640
628	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
629	in the init function, monitor the original port. This two-way monitoring	642	port, and in the remote init function, immediately monitor the passed
630	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<$initfunc> has no visible effects on the
		647	caller before C<spawn> returns (by delaying invocation when spawn is
		648	called for the local node).
631		649
632	Example: spawn a chat server port on C<$othernode>.	650	Example: spawn a chat server port on C<$othernode>.
633		651
634	# this node, executed from within a port context:	652	# this node, executed from within a port context:
635	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
650		668
651	sub _spawn {	669	sub _spawn {
652	my $port = shift;	670	my $port = shift;
653	my $init = shift;	671	my $init = shift;
654		672
		673	# rcv will create the actual port
655	local $SELF = "$NODE#$port";	674	local $SELF = "$NODE#$port";
656	eval {	675	eval {
657	&{ load_func $init }	676	&{ load_func $init }
658	};	677	};
659	_self_die if $@;	678	_self_die if $@;
660	}	679	}
661		680
662	sub spawn(@) {	681	sub spawn(@) {
663	my ($noderef, undef) = split /#/, shift, 2;	682	my ($nodeid, undef) = split /#/, shift, 2;
664		683
665	my $id = "$RUNIQ." . $ID++;	684	my $id = "$RUNIQ." . $ID++;
666		685
667	$_[0] =~ /::/	686	$_[0] =~ /::/
668	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";
669		688
670	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
671		690
672	"$noderef#$id"	691	"$nodeid#$id"
673	}	692	}
674		693
675	=item after $timeout, @msg	694	=item after $timeout, @msg
676		695
677	=item after $timeout, $callback	696	=item after $timeout, $callback
678		697
679	Either sends the given message, or call the given callback, after the	698	Either sends the given message, or call the given callback, after the
680	specified number of seconds.	699	specified number of seconds.
681		700
682	This is simply a utility function that come sin handy at times.	701	This is simply a utility function that comes in handy at times - the
		702	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		703	so it may go away in the future.
683		704
684	=cut	705	=cut
685		706
686	sub after($@) {	707	sub after($@) {
687	my ($timeout, @action) = @_;	708	my ($timeout, @action) = @_;
…		…
692	? $action[0]()	713	? $action[0]()
693	: snd @action;	714	: snd @action;
694	};	715	};
695	}	716	}
696		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
		768	}
		769
697	=back	770	=back
698		771
699	=head1 AnyEvent::MP vs. Distributed Erlang	772	=head1 AnyEvent::MP vs. Distributed Erlang
700		773
701	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	774	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
…		…
710		783
711	Despite the similarities, there are also some important differences:	784	Despite the similarities, there are also some important differences:
712		785
713	=over 4	786	=over 4
714		787
715	=item * Node references contain the recipe on how to contact them.	788	=item * Node IDs are arbitrary strings in AEMP.
716		789
717	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
718	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
719	convenience functionality.	792	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		793
724	=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
725	uses "local ports are like remote ports".	795	uses "local ports are like remote ports".
726		796
727	The failure modes for local ports are quite different (runtime errors	797	The failure modes for local ports are quite different (runtime errors
…		…
740		810
741	Erlang uses processes that selectively receive messages, and therefore	811	Erlang uses processes that selectively receive messages, and therefore
742	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
743	useful purpose. For the same reason the pattern-matching abilities of	813	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	814	AnyEvent::MP are more limited, as there is little need to be able to
745	filter messages without dequeing them.	815	filter messages without dequeuing them.
746		816
747	(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).
748		818
749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	819	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
750		820
…		…
756		826
757	Erlang makes few guarantees on messages delivery - messages can get lost	827	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,	828	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).	829	and c, and the other side only receives messages a and c).
760		830
761	AEMP guarantees correct ordering, and the guarantee that there are no	831	AEMP guarantees correct ordering, and the guarantee that after one message
762	holes in the message sequence.	832	is lost, all following ones sent to the same port are lost as well, until
763		833	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	834	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		835
775	=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.
776		837
777	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
778	known to other nodes for a completely different process, causing messages	839	known to other nodes for a completely different process, causing messages
…		…
782	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.
783		844
784	=item * Erlang uses unprotected connections, AEMP uses secure	845	=item * Erlang uses unprotected connections, AEMP uses secure
785	authentication and can use TLS.	846	authentication and can use TLS.
786		847
787	AEMP can use a proven protocol - SSL/TLS - to protect connections and	848	AEMP can use a proven protocol - TLS - to protect connections and
788	securely authenticate nodes.	849	securely authenticate nodes.
789		850
790	=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
791	communications.	852	communications.
792		853
793	The AEMP protocol, unlike the Erlang protocol, supports both	854	The AEMP protocol, unlike the Erlang protocol, supports both programming
794	language-independent text-only protocols (good for debugging) and binary,	855	language independent text-only protocols (good for debugging) and binary,
795	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.
796		858
797	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
798	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
799	protocol simple.	861	protocol simple.
800		862
801	=item * AEMP has more flexible monitoring options than Erlang.	863	=item * AEMP has more flexible monitoring options than Erlang.
802		864
803	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
…		…
806	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
807	on a per-process basis.	869	on a per-process basis.
808		870
809	=item * Erlang tries to hide remote/local connections, AEMP does not.	871	=item * Erlang tries to hide remote/local connections, AEMP does not.
810		872
811	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
812	as linking is (except linking is unreliable in Erlang).	874	same way as linking is (except linking is unreliable in Erlang).
813		875
814	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
815	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
816	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
817	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
818	more reliable.	880	reliable (no need for C<spawn_link>).
819		881
820	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
821	(hard to do in Erlang).	883	(hard to do in Erlang).
822		884
823	=back	885	=back
824		886
825	=head1 RATIONALE	887	=head1 RATIONALE
826		888
827	=over 4	889	=over 4
828		890
829	=item Why strings for ports and noderefs, why not objects?	891	=item Why strings for port and node IDs, why not objects?
830		892
831	We considered "objects", but found that the actual number of methods	893	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	894	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	895	the network frequently, the serialising/deserialising would add lots of
834	overhead, as well as having to keep a proxy object.	896	overhead, as well as having to keep a proxy object everywhere.
835		897
836	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
837	procedures to be "valid".	899	procedures to be "valid".
838		900
839	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
840	can't become much cheaper.	902	global hash - it can't become much cheaper.
841		903
842	=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?
843		905
844	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
845	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
846	default.	908	default (although all nodes will accept it).
847		909
848	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
849	faster for small messages and b) most importantly, after years of	911	faster for small messages and b) most importantly, after years of
850	experience we found that object serialisation is causing more problems	912	experience we found that object serialisation is causing more problems
851	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
852	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
853	always have to re-think your design.	915	always have to re-think your design.
854		916
855	Keeping your messages simple, concentrating on data structures rather than	917	Keeping your messages simple, concentrating on data structures rather than
856	objects, will keep your messages clean, tidy and efficient.	918	objects, will keep your messages clean, tidy and efficient.
857		919
858	=back	920	=back
859		921
860	=head1 SEE ALSO	922	=head1 SEE ALSO
861		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
862	L<AnyEvent>.	934	L<AnyEvent>.
863		935
864	=head1 AUTHOR	936	=head1 AUTHOR
865		937
866	Marc Lehmann <schmorp@schmorp.de>	938	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 1.88 by root, Fri Sep 11 15:02:17 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 1.88 by root, Fri Sep 11 15:02:17 2009 UTC