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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC vs.
Revision 1.87 by root, Fri Sep 11 02:32:23 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;	15	configure;
17		16
18	# ports are message endpoints	17	# ports are message destinations
19		18
20	# sending messages	19	# sending messages
21	snd $port, type => data...;	20	snd $port, type => data...;
22	snd $port, @msg;	21	snd $port, @msg;
23	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
24		23
25	# creating/using ports, the simple way	24	# creating/using ports, the simple way
26	my $simple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
27		26
28	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
29	my $port = port;	28	my $port = port;
30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
31	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
32		31
33	# create a port on another node	32	# create a port on another node
34	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
35		34
36	# monitoring	35	# monitoring
…		…
38	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
39	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
40		39
41	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
42		41
		42	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work	43	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - WIP
46	AnyEvent::MP::Transport - mostly stable	45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
47		47
48	stay tuned.	48	stay tuned.
49		49
50	=head1 DESCRIPTION	50	=head1 DESCRIPTION
51		51
52	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
53		53
54	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
55	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
56		56
57	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>
58	manual page.	58	manual page and the examples under F<eg/>.
59
60	At the moment, this module family is severly broken and underdocumented,
61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
62	stay tuned!
63		59
64	=head1 CONCEPTS	60	=head1 CONCEPTS
65		61
66	=over 4	62	=over 4
67		63
68	=item port	64	=item port
69		65
70	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).
71		68
72	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
73	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.
74		72
75	=item port ID - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
76		74
77	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
78	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
79	exception is the the node port, whose ID is identical to its node
80	reference.
81		77
82	=item node	78	=item node
83		79
84	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,
85	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
86	ports.	82	ports.
87		83
88	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
89	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
90	from any other node).	86	currently.
91		87
92	=item node ID - C<[a-za-Z0-9_\-.:]+>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
93		89
94	A node ID is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
95	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
96	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.
97		94
98	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
99	TCP/IP, other protocols might look different).
100		96
101	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
102	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.
103		101
104	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
105	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 an 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.
106		129
107	=back	130	=back
108		131
109	=head1 VARIABLES/FUNCTIONS	132	=head1 VARIABLES/FUNCTIONS
110		133
…		…
126		149
127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
128		151
129	our @EXPORT = qw(	152	our @EXPORT = qw(
130	NODE $NODE *SELF node_of after	153	NODE $NODE *SELF node_of after
131	resolve_node initialise_node	154	configure
132	snd rcv mon mon_guard kil reg psub spawn	155	snd rcv mon mon_guard kil reg psub spawn cal
133	port	156	port
134	);	157	);
135		158
136	our $SELF;	159	our $SELF;
137		160
…		…
141	kil $SELF, die => $msg;	164	kil $SELF, die => $msg;
142	}	165	}
143		166
144	=item $thisnode = NODE / $NODE	167	=item $thisnode = NODE / $NODE
145		168
146	The C<NODE> function returns, and the C<$NODE> variable contains the	169	The C<NODE> function returns, and the C<$NODE> variable contains, the node
147	node id 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
148	C<initialise_node>.	171	a call to C<configure>.
149		172
150	=item $nodeid = node_of $port	173	=item $nodeid = node_of $port
151		174
152	Extracts and returns the noderef from a port ID or a node ID.	175	Extracts and returns the node ID from a port ID or a node ID.
153		176
154	=item initialise_node $profile_name	177	=item configure $profile, key => value...
155		178
		179	=item configure key => value...
		180
156	Before a node can talk to other nodes on the network it has to initialise	181	Before a node can talk to other nodes on the network (i.e. enter
157	itself - the minimum a node needs to know is it's own name, and optionally	182	"distributed mode") it has to configure itself - the minimum a node needs
158	it should know the noderefs of some other nodes in the network.	183	to know is its own name, and optionally it should know the addresses of
		184	some other nodes in the network to discover other nodes.
159		185
160	This function initialises a node - it must be called exactly once (or	186	This function configures a node - it must be called exactly once (or
161	never) before calling other AnyEvent::MP functions.	187	never) before calling other AnyEvent::MP functions.
162		188
163	All arguments (optionally except for the first) are noderefs, which can be
164	either resolved or unresolved.
165
166	The first argument will be looked up in the configuration database first
167	(if it is C<undef> then the current nodename will be used instead) to find
168	the relevant configuration profile (see L<aemp>). If none is found then
169	the default configuration is used. The configuration supplies additional
170	seed/master nodes and can override the actual noderef.
171
172	There are two types of networked nodes, public nodes and slave nodes:
173
174	=over 4	189	=over 4
175		190
176	=item public nodes	191	=item step 1, gathering configuration from profiles
177		192
178	For public nodes, C<$noderef> (supplied either directly to	193	The function first looks up a profile in the aemp configuration (see the
179	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
180	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.
181		197
182	After resolving, the node will bind itself on all endpoints.	198	The profile data is then gathered as follows:
183		199
184	=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).
185		205
186	When the C<$noderef> (either as given or overriden by the config file)	206	That means that the values specified in the profile have highest priority
187	is the special string C<slave/>, then the node will become a slave	207	and the values specified directly via C<configure> have lowest priority,
188	node. Slave nodes cannot be contacted from outside, and cannot talk to	208	and can only be used to specify defaults.
189	each other (at least in this version of AnyEvent::MP).
190		209
191	Slave nodes work by creating connections to all public nodes, using the	210	If the profile specifies a node ID, then this will become the node ID of
192	L<AnyEvent::MP::Global> service.	211	this process. If not, then the profile name will be used as node ID. The
		212	special node ID of C<anon/> will be replaced by a random node ID.
		213
		214	=item step 2, bind listener sockets
		215
		216	The next step is to look up the binds in the profile, followed by binding
		217	aemp protocol listeners on all binds specified (it is possible and valid
		218	to have no binds, meaning that the node cannot be contacted form the
		219	outside. This means the node cannot talk to other nodes that also have no
		220	binds, but it can still talk to all "normal" nodes).
		221
		222	If the profile does not specify a binds list, then a default of C<*> is
		223	used, meaning the node will bind on a dynamically-assigned port on every
		224	local IP address it finds.
		225
		226	=item step 3, connect to seed nodes
		227
		228	As the last step, the seeds list from the profile is passed to the
		229	L<AnyEvent::MP::Global> module, which will then use it to keep
		230	connectivity with at least one node at any point in time.
193		231
194	=back	232	=back
195		233
196	After initialising itself, the node will connect to all additional	234	Example: become a distributed node using the local node name as profile.
197	C<$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.
198	optional and can be used to quickly bootstrap the node into an existing
199	network.
200		236
201	All the seednodes will also be specially marked to automatically retry	237	configure
202	connecting to them indefinitely, so make sure that seednodes are really
203	reliable and up (this might also change in the future).
204		238
205	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
206	specified via C<aemp> for the current node. This should be the most common	240	clients.
207	form of invocation for "daemon"-type nodes.
208		241
209	initialise_node;	242	configure nodeid => "anon/";
210		243
211	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
212	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).
213		247
214	initialise_node "slave/";	248	# use the aemp commandline utility
		249	# aemp profile seed nodeid anon/ binds '*:4040'
215		250
216	Example: become a public node, and try to contact some well-known master	251	# then use it
217	servers to become part of the network.	252	configure profile => "seed";
218		253
219	initialise_node undef, "master1", "master2";	254	# or simply use aemp from the shell again:
		255	# aemp run profile seed
220		256
221	Example: become a public node listening on port C<4041>.	257	# or provide a nicer-to-remember nodeid
222		258	# aemp run profile seed nodeid "$(hostname)"
223	initialise_node 4041;
224
225	Example: become a public node, only visible on localhost port 4044.
226
227	initialise_node "localhost:4044";
228
229	=item $cv = resolve_node $noderef
230
231	Takes an unresolved node reference that may contain hostnames and
232	abbreviated IDs, resolves all of them and returns a resolved node
233	reference.
234
235	In addition to C<address:port> pairs allowed in resolved noderefs, the
236	following forms are supported:
237
238	=over 4
239
240	=item the empty string
241
242	An empty-string component gets resolved as if the default port (4040) was
243	specified.
244
245	=item naked port numbers (e.g. C<1234>)
246
247	These are resolved by prepending the local nodename and a colon, to be
248	further resolved.
249
250	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
251
252	These are resolved by using AnyEvent::DNS to resolve them, optionally
253	looking up SRV records for the C<aemp=4040> port, if no port was
254	specified.
255
256	=back
257		259
258	=item $SELF	260	=item $SELF
259		261
260	Contains the current port id while executing C<rcv> callbacks or C<psub>	262	Contains the current port id while executing C<rcv> callbacks or C<psub>
261	blocks.	263	blocks.
262		264
263	=item SELF, %SELF, @SELF...	265	=item *SELF, SELF, %SELF, @SELF...
264		266
265	Due to some quirks in how perl exports variables, it is impossible to	267	Due to some quirks in how perl exports variables, it is impossible to
266	just export C<$SELF>, all the symbols called C<SELF> are exported by this	268	just export C<$SELF>, all the symbols named C<SELF> are exported by this
267	module, but only C<$SELF> is currently used.	269	module, but only C<$SELF> is currently used.
268		270
269	=item snd $port, type => @data	271	=item snd $port, type => @data
270		272
271	=item snd $port, @msg	273	=item snd $port, @msg
272		274
273	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
274	a local or a remote port, and must be a port ID.	276	local or a remote port, and must be a port ID.
275		277
276	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
277	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
278	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.
279		282
280	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
281	function: modifying any argument is not allowed and can cause many	284	function: modifying any argument (or values referenced by them) is
282	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.
283		289
284	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
285	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
286	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
287	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
288	node, anything can be passed.	294	node, anything can be passed. Best rely only on the common denominator of
		295	these.
289		296
290	=item $local_port = port	297	=item $local_port = port
291		298
292	Create a new local port object and returns its port ID. Initially it has	299	Create a new local port object and returns its port ID. Initially it has
293	no callbacks set and will throw an error when it receives messages.	300	no callbacks set and will throw an error when it receives messages.
…		…
378		385
379	=cut	386	=cut
380		387
381	sub rcv($@) {	388	sub rcv($@) {
382	my $port = shift;	389	my $port = shift;
383	my ($noderef, $portid) = split /#/, $port, 2;	390	my ($nodeid, $portid) = split /#/, $port, 2;
384		391
385	$NODE{$noderef} == $NODE{""}	392	$NODE{$nodeid} == $NODE{""}
386	or Carp::croak "$port: rcv can only be called on local ports, caught";	393	or Carp::croak "$port: rcv can only be called on local ports, caught";
387		394
388	while (@_) {	395	while (@_) {
389	if (ref $_[0]) {	396	if (ref $_[0]) {
390	if (my $self = $PORT_DATA{$portid}) {	397	if (my $self = $PORT_DATA{$portid}) {
…		…
469	$res	476	$res
470	}	477	}
471	}	478	}
472	}	479	}
473		480
474	=item $guard = mon $port, $cb->(@reason)	481	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
475		482
476	=item $guard = mon $port, $rcvport	483	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
477		484
478	=item $guard = mon $port	485	=item $guard = mon $port # kill $SELF when $port dies
479		486
480	=item $guard = mon $port, $rcvport, @msg	487	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
481		488
482	Monitor the given port and do something when the port is killed or	489	Monitor the given port and do something when the port is killed or
483	messages to it were lost, and optionally return a guard that can be used	490	messages to it were lost, and optionally return a guard that can be used
484	to stop monitoring again.	491	to stop monitoring again.
485
486	C<mon> effectively guarantees that, in the absence of hardware failures,
487	that after starting the monitor, either all messages sent to the port
488	will arrive, or the monitoring action will be invoked after possible
489	message loss has been detected. No messages will be lost "in between"
490	(after the first lost message no further messages will be received by the
491	port). After the monitoring action was invoked, further messages might get
492	delivered again.
493
494	Note that monitoring-actions are one-shot: once released, they are removed
495	and will not trigger again.
496		492
497	In the first form (callback), the callback is simply called with any	493	In the first form (callback), the callback is simply called with any
498	number of C<@reason> elements (no @reason means that the port was deleted	494	number of C<@reason> elements (no @reason means that the port was deleted
499	"normally"). Note also that I<< the callback B<must> never die >>, so use	495	"normally"). Note also that I<< the callback B<must> never die >>, so use
500	C<eval> if unsure.	496	C<eval> if unsure.
501		497
502	In the second form (another port given), the other port (C<$rcvport>)	498	In the second form (another port given), the other port (C<$rcvport>)
503	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	499	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
504	"normal" kils nothing happens, while under all other conditions, the other	500	"normal" kils nothing happens, while under all other conditions, the other
505	port is killed with the same reason.	501	port is killed with the same reason.
506		502
507	The third form (kill self) is the same as the second form, except that	503	The third form (kill self) is the same as the second form, except that
508	C<$rvport> defaults to C<$SELF>.	504	C<$rvport> defaults to C<$SELF>.
509		505
510	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
511	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.
512		511
513	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
514	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
515	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
516	even monitoring requests can get lost (for exmaple, when the connection	515	even monitoring requests can get lost (for example, when the connection
517	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
518	these problems do not exist.	517	these problems do not exist.
519		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
520	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
521		537
522	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
523		539
524	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
…		…
530	mon $port, $self => "restart";	546	mon $port, $self => "restart";
531		547
532	=cut	548	=cut
533		549
534	sub mon {	550	sub mon {
535	my ($noderef, $port) = split /#/, shift, 2;	551	my ($nodeid, $port) = split /#/, shift, 2;
536		552
537	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
538		554
539	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,';
540		556
541	unless (ref $cb) {	557	unless (ref $cb) {
542	if (@_) {	558	if (@_) {
…		…
562	is killed, the references will be freed.	578	is killed, the references will be freed.
563		579
564	Optionally returns a guard that will stop the monitoring.	580	Optionally returns a guard that will stop the monitoring.
565		581
566	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
567	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>):
568		584
569	$port->rcv (start => sub {	585	$port->rcv (start => sub {
570	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	586	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
571	undef $timer if 0.9 < rand;	587	undef $timer if 0.9 < rand;
572	});	588	});
573	});	589	});
574		590
575	=cut	591	=cut
…		…
584		600
585	=item kil $port[, @reason]	601	=item kil $port[, @reason]
586		602
587	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
588		604
589	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
590	ports will not be kileld, or even notified).	606	monitoring other ports will not necessarily die because a port dies
		607	"normally").
591		608
592	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
593	C<mon>, see below).	610	C<mon>, see above).
594		611
595	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
596	will be reported as reason C<< die => $@ >>.	613	will be reported as reason C<< die => $@ >>.
597		614
598	Transport/communication errors are reported as C<< transport_error =>	615	Transport/communication errors are reported as C<< transport_error =>
…		…
603	=item $port = spawn $node, $initfunc[, @initdata]	620	=item $port = spawn $node, $initfunc[, @initdata]
604		621
605	Creates a port on the node C<$node> (which can also be a port ID, in which	622	Creates a port on the node C<$node> (which can also be a port ID, in which
606	case it's the node where that port resides).	623	case it's the node where that port resides).
607		624
608	The port ID of the newly created port is return immediately, and it is	625	The port ID of the newly created port is returned immediately, and it is
609	permissible to immediately start sending messages or monitor the port.	626	possible to immediately start sending messages or to monitor the port.
610		627
611	After the port has been created, the init function is	628	After the port has been created, the init function is called on the remote
612	called. This function must be a fully-qualified function name	629	node, in the same context as a C<rcv> callback. This function must be a
613	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	630	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
614	program, use C<::name>.	631	specify a function in the main program, use C<::name>.
615		632
616	If the function doesn't exist, then the node tries to C<require>	633	If the function doesn't exist, then the node tries to C<require>
617	the package, then the package above the package and so on (e.g.	634	the package, then the package above the package and so on (e.g.
618	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	635	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
619	exists or it runs out of package names.	636	exists or it runs out of package names.
620		637
621	The init function is then called with the newly-created port as context	638	The init function is then called with the newly-created port as context
622	object (C<$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.
623		642
624	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
625	in the init function, monitor the original port. This two-way monitoring	644	port, and in the remote init function, immediately monitor the passed
626	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<$initfunc> has no visible effects on the
		649	caller before C<spawn> returns (by delaying invocation when spawn is
		650	called for the local node).
627		651
628	Example: spawn a chat server port on C<$othernode>.	652	Example: spawn a chat server port on C<$othernode>.
629		653
630	# this node, executed from within a port context:	654	# this node, executed from within a port context:
631	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	655	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
646		670
647	sub _spawn {	671	sub _spawn {
648	my $port = shift;	672	my $port = shift;
649	my $init = shift;	673	my $init = shift;
650		674
		675	# rcv will create the actual port
651	local $SELF = "$NODE#$port";	676	local $SELF = "$NODE#$port";
652	eval {	677	eval {
653	&{ load_func $init }	678	&{ load_func $init }
654	};	679	};
655	_self_die if $@;	680	_self_die if $@;
656	}	681	}
657		682
658	sub spawn(@) {	683	sub spawn(@) {
659	my ($noderef, undef) = split /#/, shift, 2;	684	my ($nodeid, undef) = split /#/, shift, 2;
660		685
661	my $id = "$RUNIQ." . $ID++;	686	my $id = "$RUNIQ." . $ID++;
662		687
663	$_[0] =~ /::/	688	$_[0] =~ /::/
664	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";
665		690
666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
667		692
668	"$noderef#$id"	693	"$nodeid#$id"
669	}	694	}
670		695
671	=item after $timeout, @msg	696	=item after $timeout, @msg
672		697
673	=item after $timeout, $callback	698	=item after $timeout, $callback
674		699
675	Either sends the given message, or call the given callback, after the	700	Either sends the given message, or call the given callback, after the
676	specified number of seconds.	701	specified number of seconds.
677		702
678	This is simply a utility function that come sin handy at times.	703	This is simply a utility function that comes in handy at times - the
		704	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		705	so it may go away in the future.
679		706
680	=cut	707	=cut
681		708
682	sub after($@) {	709	sub after($@) {
683	my ($timeout, @action) = @_;	710	my ($timeout, @action) = @_;
…		…
688	? $action[0]()	715	? $action[0]()
689	: snd @action;	716	: snd @action;
690	};	717	};
691	}	718	}
692		719
		720	=item cal $port, @msg, $callback[, $timeout]
		721
		722	A simple form of RPC - sends a message to the given C<$port> with the
		723	given contents (C<@msg>), but adds a reply port to the message.
		724
		725	The reply port is created temporarily just for the purpose of receiving
		726	the reply, and will be C<kil>ed when no longer needed.
		727
		728	A reply message sent to the port is passed to the C<$callback> as-is.
		729
		730	If an optional time-out (in seconds) is given and it is not C<undef>,
		731	then the callback will be called without any arguments after the time-out
		732	elapsed and the port is C<kil>ed.
		733
		734	If no time-out is given, then the local port will monitor the remote port
		735	instead, so it eventually gets cleaned-up.
		736
		737	Currently this function returns the temporary port, but this "feature"
		738	might go in future versions unless you can make a convincing case that
		739	this is indeed useful for something.
		740
		741	=cut
		742
		743	sub cal(@) {
		744	my $timeout = ref $_[-1] ? undef : pop;
		745	my $cb = pop;
		746
		747	my $port = port {
		748	undef $timeout;
		749	kil $SELF;
		750	&$cb;
		751	};
		752
		753	if (defined $timeout) {
		754	$timeout = AE::timer $timeout, 0, sub {
		755	undef $timeout;
		756	kil $port;
		757	$cb->();
		758	};
		759	} else {
		760	mon $_[0], sub {
		761	kil $port;
		762	$cb->();
		763	};
		764	}
		765
		766	push @_, $port;
		767	&snd;
		768
		769	$port
		770	}
		771
693	=back	772	=back
694		773
695	=head1 AnyEvent::MP vs. Distributed Erlang	774	=head1 AnyEvent::MP vs. Distributed Erlang
696		775
697	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	776	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
…		…
706		785
707	Despite the similarities, there are also some important differences:	786	Despite the similarities, there are also some important differences:
708		787
709	=over 4	788	=over 4
710		789
711	=item * Node references contain the recipe on how to contact them.	790	=item * Node IDs are arbitrary strings in AEMP.
712		791
713	Erlang relies on special naming and DNS to work everywhere in the	792	Erlang relies on special naming and DNS to work everywhere in the same
714	same way. AEMP relies on each node knowing it's own address(es), with	793	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
715	convenience functionality.	794	configuration or DNS), but will otherwise discover other odes itself.
716
717	This means that AEMP requires a less tightly controlled environment at the
718	cost of longer node references and a slightly higher management overhead.
719		795
720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	796	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
721	uses "local ports are like remote ports".	797	uses "local ports are like remote ports".
722		798
723	The failure modes for local ports are quite different (runtime errors	799	The failure modes for local ports are quite different (runtime errors
…		…
736		812
737	Erlang uses processes that selectively receive messages, and therefore	813	Erlang uses processes that selectively receive messages, and therefore
738	needs a queue. AEMP is event based, queuing messages would serve no	814	needs a queue. AEMP is event based, queuing messages would serve no
739	useful purpose. For the same reason the pattern-matching abilities of	815	useful purpose. For the same reason the pattern-matching abilities of
740	AnyEvent::MP are more limited, as there is little need to be able to	816	AnyEvent::MP are more limited, as there is little need to be able to
741	filter messages without dequeing them.	817	filter messages without dequeuing them.
742		818
743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	819	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
744		820
745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	821	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
746		822
…		…
752		828
753	Erlang makes few guarantees on messages delivery - messages can get lost	829	Erlang makes few guarantees on messages delivery - messages can get lost
754	without any of the processes realising it (i.e. you send messages a, b,	830	without any of the processes realising it (i.e. you send messages a, b,
755	and c, and the other side only receives messages a and c).	831	and c, and the other side only receives messages a and c).
756		832
757	AEMP guarantees correct ordering, and the guarantee that there are no	833	AEMP guarantees correct ordering, and the guarantee that after one message
758	holes in the message sequence.	834	is lost, all following ones sent to the same port are lost as well, until
759		835	monitoring raises an error, so there are no silent "holes" in the message
760	=item * In Erlang, processes can be declared dead and later be found to be	836	sequence.
761	alive.
762
763	In Erlang it can happen that a monitored process is declared dead and
764	linked processes get killed, but later it turns out that the process is
765	still alive - and can receive messages.
766
767	In AEMP, when port monitoring detects a port as dead, then that port will
768	eventually be killed - it cannot happen that a node detects a port as dead
769	and then later sends messages to it, finding it is still alive.
770		837
771	=item * Erlang can send messages to the wrong port, AEMP does not.	838	=item * Erlang can send messages to the wrong port, AEMP does not.
772		839
773	In Erlang it is quite likely that a node that restarts reuses a process ID	840	In Erlang it is quite likely that a node that restarts reuses a process ID
774	known to other nodes for a completely different process, causing messages	841	known to other nodes for a completely different process, causing messages
…		…
778	around in the network will not be sent to an unrelated port.	845	around in the network will not be sent to an unrelated port.
779		846
780	=item * Erlang uses unprotected connections, AEMP uses secure	847	=item * Erlang uses unprotected connections, AEMP uses secure
781	authentication and can use TLS.	848	authentication and can use TLS.
782		849
783	AEMP can use a proven protocol - SSL/TLS - to protect connections and	850	AEMP can use a proven protocol - TLS - to protect connections and
784	securely authenticate nodes.	851	securely authenticate nodes.
785		852
786	=item * The AEMP protocol is optimised for both text-based and binary	853	=item * The AEMP protocol is optimised for both text-based and binary
787	communications.	854	communications.
788		855
789	The AEMP protocol, unlike the Erlang protocol, supports both	856	The AEMP protocol, unlike the Erlang protocol, supports both programming
790	language-independent text-only protocols (good for debugging) and binary,	857	language independent text-only protocols (good for debugging) and binary,
791	language-specific serialisers (e.g. Storable).	858	language-specific serialisers (e.g. Storable). By default, unless TLS is
		859	used, the protocol is actually completely text-based.
792		860
793	It has also been carefully designed to be implementable in other languages	861	It has also been carefully designed to be implementable in other languages
794	with a minimum of work while gracefully degrading fucntionality to make the	862	with a minimum of work while gracefully degrading functionality to make the
795	protocol simple.	863	protocol simple.
796		864
797	=item * AEMP has more flexible monitoring options than Erlang.	865	=item * AEMP has more flexible monitoring options than Erlang.
798		866
799	In Erlang, you can chose to receive I<all> exit signals as messages	867	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
802	Erlang, as one can choose between automatic kill, exit message or callback	870	Erlang, as one can choose between automatic kill, exit message or callback
803	on a per-process basis.	871	on a per-process basis.
804		872
805	=item * Erlang tries to hide remote/local connections, AEMP does not.	873	=item * Erlang tries to hide remote/local connections, AEMP does not.
806		874
807	Monitoring in Erlang is not an indicator of process death/crashes,	875	Monitoring in Erlang is not an indicator of process death/crashes, in the
808	as linking is (except linking is unreliable in Erlang).	876	same way as linking is (except linking is unreliable in Erlang).
809		877
810	In AEMP, you don't "look up" registered port names or send to named ports	878	In AEMP, you don't "look up" registered port names or send to named ports
811	that might or might not be persistent. Instead, you normally spawn a port	879	that might or might not be persistent. Instead, you normally spawn a port
812	on the remote node. The init function monitors the you, and you monitor	880	on the remote node. The init function monitors you, and you monitor the
813	the remote port. Since both monitors are local to the node, they are much	881	remote port. Since both monitors are local to the node, they are much more
814	more reliable.	882	reliable (no need for C<spawn_link>).
815		883
816	This also saves round-trips and avoids sending messages to the wrong port	884	This also saves round-trips and avoids sending messages to the wrong port
817	(hard to do in Erlang).	885	(hard to do in Erlang).
818		886
819	=back	887	=back
820		888
821	=head1 RATIONALE	889	=head1 RATIONALE
822		890
823	=over 4	891	=over 4
824		892
825	=item Why strings for ports and noderefs, why not objects?	893	=item Why strings for port and node IDs, why not objects?
826		894
827	We considered "objects", but found that the actual number of methods	895	We considered "objects", but found that the actual number of methods
828	thatc an be called are very low. Since port IDs and noderefs travel over	896	that can be called are quite low. Since port and node IDs travel over
829	the network frequently, the serialising/deserialising would add lots of	897	the network frequently, the serialising/deserialising would add lots of
830	overhead, as well as having to keep a proxy object.	898	overhead, as well as having to keep a proxy object everywhere.
831		899
832	Strings can easily be printed, easily serialised etc. and need no special	900	Strings can easily be printed, easily serialised etc. and need no special
833	procedures to be "valid".	901	procedures to be "valid".
834		902
835	And a a miniport consists of a single closure stored in a global hash - it	903	And as a result, a miniport consists of a single closure stored in a
836	can't become much cheaper.	904	global hash - it can't become much cheaper.
837		905
838	=item Why favour JSON, why not real serialising format such as Storable?	906	=item Why favour JSON, why not a real serialising format such as Storable?
839		907
840	In fact, any AnyEvent::MP node will happily accept Storable as framing	908	In fact, any AnyEvent::MP node will happily accept Storable as framing
841	format, but currently there is no way to make a node use Storable by	909	format, but currently there is no way to make a node use Storable by
842	default.	910	default (although all nodes will accept it).
843		911
844	The default framing protocol is JSON because a) JSON::XS is many times	912	The default framing protocol is JSON because a) JSON::XS is many times
845	faster for small messages and b) most importantly, after years of	913	faster for small messages and b) most importantly, after years of
846	experience we found that object serialisation is causing more problems	914	experience we found that object serialisation is causing more problems
847	than it gains: Just like function calls, objects simply do not travel	915	than it solves: Just like function calls, objects simply do not travel
848	easily over the network, mostly because they will always be a copy, so you	916	easily over the network, mostly because they will always be a copy, so you
849	always have to re-think your design.	917	always have to re-think your design.
850		918
851	Keeping your messages simple, concentrating on data structures rather than	919	Keeping your messages simple, concentrating on data structures rather than
852	objects, will keep your messages clean, tidy and efficient.	920	objects, will keep your messages clean, tidy and efficient.
853		921
854	=back	922	=back
855		923
856	=head1 SEE ALSO	924	=head1 SEE ALSO
857		925
		926	L<AnyEvent::MP::Intro> - a gentle introduction.
		927
		928	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		929
		930	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		931	your applications.
		932
		933	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		934	all nodes.
		935
858	L<AnyEvent>.	936	L<AnyEvent>.
859		937
860	=head1 AUTHOR	938	=head1 AUTHOR
861		939
862	Marc Lehmann <schmorp@schmorp.de>	940	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC vs. Revision 1.87 by root, Fri Sep 11 02:32:23 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC vs.
Revision 1.87 by root, Fri Sep 11 02:32:23 2009 UTC