[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 1.100 by root, Fri Oct 2 20:41:56 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
15	# initialise the node so it can send/receive messages	14	# initialise the node so it can send/receive messages
16	initialise_node;	15	configure;
17		16
18	# ports are message endpoints	17	# ports are message destinations
19		18
20	# sending messages	19	# sending messages
21	snd $port, type => data...;	20	snd $port, type => data...;
22	snd $port, @msg;	21	snd $port, @msg;
23	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
24		23
25	# creating/using ports, the simple way	24	# creating/using ports, the simple way
26	my $simple_port = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
27		26
28	# creating/using ports, tagged message matching	27	# creating/using ports, tagged message matching
29	my $port = port;	28	my $port = port;
30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
31	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
32		31
33	# create a port on another node	32	# create a port on another node
34	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
35		34
36	# monitoring	35	# monitoring
37	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $localport, $cb->(@msg) # callback is invoked on death
38	mon $port, $otherport # kill otherport on abnormal death	37	mon $localport, $otherport # kill otherport on abnormal death
39	mon $port, $otherport, @msg # send message on death	38	mon $localport, $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 API.
47		46	AnyEvent::MP::Global - stable API.
48	stay tuned.
49		47
50	=head1 DESCRIPTION	48	=head1 DESCRIPTION
51		49
52	This module (-family) implements a simple message passing framework.	50	This module (-family) implements a simple message passing framework.
53		51
54	Despite its simplicity, you can securely message other processes running	52	Despite its simplicity, you can securely message other processes running
55	on the same or other hosts.	53	on the same or other hosts, and you can supervise entities remotely.
56		54
57	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>
58	manual page.	56	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		57
64	=head1 CONCEPTS	58	=head1 CONCEPTS
65		59
66	=over 4	60	=over 4
67		61
68	=item port	62	=item port
69		63
70	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).
71		66
72	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
73	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.
74		70
75	=item port ID - C<noderef#portname>	71	=item port ID - C<nodeid#portname>
76		72
77	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
78	separator, and a port name (a printable string of unspecified format). An	74	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		75
82	=item node	76	=item node
83		77
84	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,
85	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
86	ports.	80	ports.
87		81
88	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
89	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
90	from any other node).	84	currently.
91		85
92	=item node ID - C<[a-za-Z0-9_\-.:]+>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
93		87
94	A node ID is a string that either simply identifies the node (for	88	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	89	network. Depending on the configuration used, node IDs can look like a
96	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.
97		92
98	This recipe is simply a comma-separated list of C<address:port> pairs (for	93	=item binds - C<ip:port>
99	TCP/IP, other protocols might look different).
100		94
101	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
102	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.
103		99
104	Before using an unresolved node reference in a message you first have to	100	=item seed nodes
105	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 that 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.
106		127
107	=back	128	=back
108		129
109	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
110		131
122		143
123	use AE ();	144	use AE ();
124		145
125	use base "Exporter";	146	use base "Exporter";
126		147
127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	148	our $VERSION = 1.21;
128		149
129	our @EXPORT = qw(	150	our @EXPORT = qw(
130	NODE $NODE *SELF node_of after	151	NODE $NODE *SELF node_of after
131	resolve_node initialise_node	152	configure
132	snd rcv mon mon_guard kil reg psub spawn	153	snd rcv mon mon_guard kil psub spawn cal
133	port	154	port
134	);	155	);
135		156
136	our $SELF;	157	our $SELF;
137		158
…		…
141	kil $SELF, die => $msg;	162	kil $SELF, die => $msg;
142	}	163	}
143		164
144	=item $thisnode = NODE / $NODE	165	=item $thisnode = NODE / $NODE
145		166
146	The C<NODE> function returns, and the C<$NODE> variable contains the	167	The C<NODE> function returns, and the C<$NODE> variable contains, the node
147	node id 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
148	C<initialise_node>.	169	a call to C<configure>.
149		170
150	=item $nodeid = node_of $port	171	=item $nodeid = node_of $port
151		172
152	Extracts and returns the noderef from a port ID or a node ID.	173	Extracts and returns the node ID from a port ID or a node ID.
153		174
154	=item initialise_node $profile_name	175	=item configure $profile, key => value...
155		176
		177	=item configure key => value...
		178
156	Before a node can talk to other nodes on the network it has to initialise	179	Before a node can talk to other nodes on the network (i.e. enter
157	itself - the minimum a node needs to know is it's own name, and optionally	180	"distributed mode") it has to configure itself - the minimum a node needs
158	it should know the noderefs of some other nodes in the network.	181	to know is its own name, and optionally it should know the addresses of
		182	some other nodes in the network to discover other nodes.
159		183
160	This function initialises a node - it must be called exactly once (or	184	This function configures a node - it must be called exactly once (or
161	never) before calling other AnyEvent::MP functions.	185	never) before calling other AnyEvent::MP functions.
162		186
163	All arguments (optionally except for the first) are noderefs, which can be
164	either resolved or unresolved.
165
166	The first argument will be looked up in the configuration database first
167	(if it is C<undef> then the current nodename will be used instead) to find
168	the relevant configuration profile (see L<aemp>). If none is found then
169	the default configuration is used. The configuration supplies additional
170	seed/master nodes and can override the actual noderef.
171
172	There are two types of networked nodes, public nodes and slave nodes:
173
174	=over 4	187	=over 4
175		188
176	=item public nodes	189	=item step 1, gathering configuration from profiles
177		190
178	For public nodes, C<$noderef> (supplied either directly to	191	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	192	L<aemp> commandline utility). The profile name can be specified via the
180	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.
181		195
182	After resolving, the node will bind itself on all endpoints.	196	The profile data is then gathered as follows:
183		197
184	=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).
185		203
186	When the C<$noderef> (either as given or overriden by the config file)	204	That means that the values specified in the profile have highest priority
187	is the special string C<slave/>, then the node will become a slave	205	and the values specified directly via C<configure> have lowest priority,
188	node. Slave nodes cannot be contacted from outside, and cannot talk to	206	and can only be used to specify defaults.
189	each other (at least in this version of AnyEvent::MP).
190		207
191	Slave nodes work by creating connections to all public nodes, using the	208	If the profile specifies a node ID, then this will become the node ID of
192	L<AnyEvent::MP::Global> service.	209	this process. If not, then the profile name will be used as node ID. The
		210	special node ID of C<anon/> will be replaced by a random node ID.
		211
		212	=item step 2, bind listener sockets
		213
		214	The next step is to look up the binds in the profile, followed by binding
		215	aemp protocol listeners on all binds specified (it is possible and valid
		216	to have no binds, meaning that the node cannot be contacted form the
		217	outside. This means the node cannot talk to other nodes that also have no
		218	binds, but it can still talk to all "normal" nodes).
		219
		220	If the profile does not specify a binds list, then a default of C<*> is
		221	used, meaning the node will bind on a dynamically-assigned port on every
		222	local IP address it finds.
		223
		224	=item step 3, connect to seed nodes
		225
		226	As the last step, the seeds list from the profile is passed to the
		227	L<AnyEvent::MP::Global> module, which will then use it to keep
		228	connectivity with at least one node at any point in time.
193		229
194	=back	230	=back
195		231
196	After initialising itself, the node will connect to all additional	232	Example: become a distributed node using the local node name as profile.
197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are	233	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		234
201	All the seednodes will also be specially marked to automatically retry	235	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		236
205	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
206	specified via C<aemp> for the current node. This should be the most common	238	clients.
207	form of invocation for "daemon"-type nodes.
208		239
209	initialise_node;	240	configure nodeid => "anon/";
210		241
211	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
212	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).
213		245
214	initialise_node "slave/";	246	# use the aemp commandline utility
		247	# aemp profile seed nodeid anon/ binds '*:4040'
215		248
216	Example: become a public node, and try to contact some well-known master	249	# then use it
217	servers to become part of the network.	250	configure profile => "seed";
218		251
219	initialise_node undef, "master1", "master2";	252	# or simply use aemp from the shell again:
		253	# aemp run profile seed
220		254
221	Example: become a public node listening on port C<4041>.	255	# or provide a nicer-to-remember nodeid
222		256	# 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		257
258	=item $SELF	258	=item $SELF
259		259
260	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
261	blocks.	261	blocks.
262		262
263	=item SELF, %SELF, @SELF...	263	=item *SELF, SELF, %SELF, @SELF...
264		264
265	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
266	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols named C<SELF> are exported by this
267	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
268		268
269	=item snd $port, type => @data	269	=item snd $port, type => @data
270		270
271	=item snd $port, @msg	271	=item snd $port, @msg
272		272
273	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
274	a local or a remote port, and must be a port ID.	274	local or a remote port, and must be a port ID.
275		275
276	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
277	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
278	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.
279		280
280	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
281	function: modifying any argument is not allowed and can cause many	282	function: modifying any argument (or values referenced by them) is
282	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.
283		287
284	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
285	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
286	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
287	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
288	node, anything can be passed.	292	node, anything can be passed. Best rely only on the common denominator of
		293	these.
289		294
290	=item $local_port = port	295	=item $local_port = port
291		296
292	Create a new local port object and returns its port ID. Initially it has	297	Create a new local port object and returns its port ID. Initially it has
293	no callbacks set and will throw an error when it receives messages.	298	no callbacks set and will throw an error when it receives messages.
…		…
378		383
379	=cut	384	=cut
380		385
381	sub rcv($@) {	386	sub rcv($@) {
382	my $port = shift;	387	my $port = shift;
383	my ($noderef, $portid) = split /#/, $port, 2;	388	my ($nodeid, $portid) = split /#/, $port, 2;
384		389
385	$NODE{$noderef} == $NODE{""}	390	$NODE{$nodeid} == $NODE{""}
386	or Carp::croak "$port: rcv can only be called on local ports, caught";	391	or Carp::croak "$port: rcv can only be called on local ports, caught";
387		392
388	while (@_) {	393	while (@_) {
389	if (ref $_[0]) {	394	if (ref $_[0]) {
390	if (my $self = $PORT_DATA{$portid}) {	395	if (my $self = $PORT_DATA{$portid}) {
…		…
469	$res	474	$res
470	}	475	}
471	}	476	}
472	}	477	}
473		478
474	=item $guard = mon $port, $cb->(@reason)	479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
475		480
476	=item $guard = mon $port, $rcvport	481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
477		482
478	=item $guard = mon $port	483	=item $guard = mon $port # kill $SELF when $port dies
479		484
480	=item $guard = mon $port, $rcvport, @msg	485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
481		486
482	Monitor the given port and do something when the port is killed or	487	Monitor the given port and do something when the port is killed or
483	messages to it were lost, and optionally return a guard that can be used	488	messages to it were lost, and optionally return a guard that can be used
484	to stop monitoring again.	489	to stop monitoring again.
485
486	C<mon> effectively guarantees that, in the absence of hardware failures,
487	that after starting the monitor, either all messages sent to the port
488	will arrive, or the monitoring action will be invoked after possible
489	message loss has been detected. No messages will be lost "in between"
490	(after the first lost message no further messages will be received by the
491	port). After the monitoring action was invoked, further messages might get
492	delivered again.
493
494	Note that monitoring-actions are one-shot: once released, they are removed
495	and will not trigger again.
496		490
497	In the first form (callback), the callback is simply called with any	491	In the first form (callback), the callback is simply called with any
498	number of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
499	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
500	C<eval> if unsure.	494	C<eval> if unsure.
501		495
502	In the second form (another port given), the other port (C<$rcvport>)	496	In the second form (another port given), the other port (C<$rcvport>)
503	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
504	"normal" kils nothing happens, while under all other conditions, the other	498	"normal" kils nothing happens, while under all other conditions, the other
505	port is killed with the same reason.	499	port is killed with the same reason.
506		500
507	The third form (kill self) is the same as the second form, except that	501	The third form (kill self) is the same as the second form, except that
508	C<$rvport> defaults to C<$SELF>.	502	C<$rvport> defaults to C<$SELF>.
509		503
510	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
511	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.
512		509
513	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
514	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
515	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
516	even monitoring requests can get lost (for exmaple, when the connection	513	even monitoring requests can get lost (for example, when the connection
517	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
518	these problems do not exist.	515	these problems do not exist.
519		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 connections).
		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
520	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
521		535
522	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
523		537
524	Example: kill ourselves when C<$port> is killed abnormally.	538	Example: kill ourselves when C<$port> is killed abnormally.
…		…
530	mon $port, $self => "restart";	544	mon $port, $self => "restart";
531		545
532	=cut	546	=cut
533		547
534	sub mon {	548	sub mon {
535	my ($noderef, $port) = split /#/, shift, 2;	549	my ($nodeid, $port) = split /#/, shift, 2;
536		550
537	my $node = $NODE{$noderef} \|\| add_node $noderef;	551	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
538		552
539	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,';
540		554
541	unless (ref $cb) {	555	unless (ref $cb) {
542	if (@_) {	556	if (@_) {
…		…
551	}	565	}
552		566
553	$node->monitor ($port, $cb);	567	$node->monitor ($port, $cb);
554		568
555	defined wantarray	569	defined wantarray
556	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	570	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
557	}	571	}
558		572
559	=item $guard = mon_guard $port, $ref, $ref...	573	=item $guard = mon_guard $port, $ref, $ref...
560		574
561	Monitors the given C<$port> and keeps the passed references. When the port	575	Monitors the given C<$port> and keeps the passed references. When the port
562	is killed, the references will be freed.	576	is killed, the references will be freed.
563		577
564	Optionally returns a guard that will stop the monitoring.	578	Optionally returns a guard that will stop the monitoring.
565		579
566	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
567	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>):
568		582
569	$port->rcv (start => sub {	583	$port->rcv (start => sub {
570	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	584	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
571	undef $timer if 0.9 < rand;	585	undef $timer if 0.9 < rand;
572	});	586	});
573	});	587	});
574		588
575	=cut	589	=cut
…		…
584		598
585	=item kil $port[, @reason]	599	=item kil $port[, @reason]
586		600
587	Kill the specified port with the given C<@reason>.	601	Kill the specified port with the given C<@reason>.
588		602
589	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
590	ports will not be kileld, or even notified).	604	monitoring other ports will not necessarily die because a port dies
		605	"normally").
591		606
592	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
593	C<mon>, see below).	608	C<mon>, see above).
594		609
595	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
596	will be reported as reason C<< die => $@ >>.	611	will be reported as reason C<< die => $@ >>.
597		612
598	Transport/communication errors are reported as C<< transport_error =>	613	Transport/communication errors are reported as C<< transport_error =>
…		…
603	=item $port = spawn $node, $initfunc[, @initdata]	618	=item $port = spawn $node, $initfunc[, @initdata]
604		619
605	Creates a port on the node C<$node> (which can also be a port ID, in which	620	Creates a port on the node C<$node> (which can also be a port ID, in which
606	case it's the node where that port resides).	621	case it's the node where that port resides).
607		622
608	The port ID of the newly created port is return immediately, and it is	623	The port ID of the newly created port is returned immediately, and it is
609	permissible to immediately start sending messages or monitor the port.	624	possible to immediately start sending messages or to monitor the port.
610		625
611	After the port has been created, the init function is	626	After the port has been created, the init function is called on the remote
612	called. This function must be a fully-qualified function name	627	node, in the same context as a C<rcv> callback. This function must be a
613	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	628	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
614	program, use C<::name>.	629	specify a function in the main program, use C<::name>.
615		630
616	If the function doesn't exist, then the node tries to C<require>	631	If the function doesn't exist, then the node tries to C<require>
617	the package, then the package above the package and so on (e.g.	632	the package, then the package above the package and so on (e.g.
618	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	633	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
619	exists or it runs out of package names.	634	exists or it runs out of package names.
620		635
621	The init function is then called with the newly-created port as context	636	The init function is then called with the newly-created port as context
622	object (C<$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.
623		640
624	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
625	in the init function, monitor the original port. This two-way monitoring	642	port, and in the remote init function, immediately monitor the passed
626	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<$initfunc> has no visible effects on the
		647	caller before C<spawn> returns (by delaying invocation when spawn is
		648	called for the local node).
627		649
628	Example: spawn a chat server port on C<$othernode>.	650	Example: spawn a chat server port on C<$othernode>.
629		651
630	# this node, executed from within a port context:	652	# this node, executed from within a port context:
631	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
646		668
647	sub _spawn {	669	sub _spawn {
648	my $port = shift;	670	my $port = shift;
649	my $init = shift;	671	my $init = shift;
650		672
		673	# rcv will create the actual port
651	local $SELF = "$NODE#$port";	674	local $SELF = "$NODE#$port";
652	eval {	675	eval {
653	&{ load_func $init }	676	&{ load_func $init }
654	};	677	};
655	_self_die if $@;	678	_self_die if $@;
656	}	679	}
657		680
658	sub spawn(@) {	681	sub spawn(@) {
659	my ($noderef, undef) = split /#/, shift, 2;	682	my ($nodeid, undef) = split /#/, shift, 2;
660		683
661	my $id = "$RUNIQ." . $ID++;	684	my $id = "$RUNIQ." . $ID++;
662		685
663	$_[0] =~ /::/	686	$_[0] =~ /::/
664	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";
665		688
666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
667		690
668	"$noderef#$id"	691	"$nodeid#$id"
669	}	692	}
670		693
671	=item after $timeout, @msg	694	=item after $timeout, @msg
672		695
673	=item after $timeout, $callback	696	=item after $timeout, $callback
674		697
675	Either sends the given message, or call the given callback, after the	698	Either sends the given message, or call the given callback, after the
676	specified number of seconds.	699	specified number of seconds.
677		700
678	This is simply a utility function that come sin handy at times.	701	This is simply a utility function that comes in handy at times - the
		702	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		703	so it may go away in the future.
679		704
680	=cut	705	=cut
681		706
682	sub after($@) {	707	sub after($@) {
683	my ($timeout, @action) = @_;	708	my ($timeout, @action) = @_;
…		…
688	? $action[0]()	713	? $action[0]()
689	: snd @action;	714	: snd @action;
690	};	715	};
691	}	716	}
692		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 (or it is C<undef>), then the local port will
		733	monitor the remote port 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
693	=back	770	=back
694		771
695	=head1 AnyEvent::MP vs. Distributed Erlang	772	=head1 AnyEvent::MP vs. Distributed Erlang
696		773
697	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
698	== aemp node, Erlang process == aemp port), so many of the documents and	775	== aemp node, Erlang process == aemp port), so many of the documents and
699	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	776	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
700	sample:	777	sample:
701		778
702	http://www.Erlang.se/doc/programming_rules.shtml	779	http://www.erlang.se/doc/programming_rules.shtml
703	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	780	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
704	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	781	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
705	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	782	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
706		783
707	Despite the similarities, there are also some important differences:	784	Despite the similarities, there are also some important differences:
708		785
709	=over 4	786	=over 4
710		787
711	=item * Node references contain the recipe on how to contact them.	788	=item * Node IDs are arbitrary strings in AEMP.
712		789
713	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
714	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
715	convenience functionality.	792	configuration or DNS), and possibly the addresses of some seed nodes, but
716		793	will otherwise discover other nodes (and their IDs) itself.
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		794
720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	795	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
721	uses "local ports are like remote ports".	796	uses "local ports are like remote ports".
722		797
723	The failure modes for local ports are quite different (runtime errors	798	The failure modes for local ports are quite different (runtime errors
…		…
736		811
737	Erlang uses processes that selectively receive messages, and therefore	812	Erlang uses processes that selectively receive messages, and therefore
738	needs a queue. AEMP is event based, queuing messages would serve no	813	needs a queue. AEMP is event based, queuing messages would serve no
739	useful purpose. For the same reason the pattern-matching abilities of	814	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	815	AnyEvent::MP are more limited, as there is little need to be able to
741	filter messages without dequeing them.	816	filter messages without dequeuing them.
742		817
743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	818	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
744		819
745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	820	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
746		821
…		…
748	so does not need a queue that can overflow). AEMP sends are immediate,	823	so does not need a queue that can overflow). AEMP sends are immediate,
749	connection establishment is handled in the background.	824	connection establishment is handled in the background.
750		825
751	=item * Erlang suffers from silent message loss, AEMP does not.	826	=item * Erlang suffers from silent message loss, AEMP does not.
752		827
753	Erlang makes few guarantees on messages delivery - messages can get lost	828	Erlang implements few guarantees on messages delivery - messages can get
754	without any of the processes realising it (i.e. you send messages a, b,	829	lost without any of the processes realising it (i.e. you send messages a,
755	and c, and the other side only receives messages a and c).	830	b, and c, and the other side only receives messages a and c).
756		831
757	AEMP guarantees correct ordering, and the guarantee that there are no	832	AEMP guarantees correct ordering, and the guarantee that after one message
758	holes in the message sequence.	833	is lost, all following ones sent to the same port are lost as well, until
759		834	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	835	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		836
771	=item * Erlang can send messages to the wrong port, AEMP does not.	837	=item * Erlang can send messages to the wrong port, AEMP does not.
772		838
773	In Erlang it is quite likely that a node that restarts reuses a process ID	839	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	840	known to other nodes for a completely different process, causing messages
…		…
778	around in the network will not be sent to an unrelated port.	844	around in the network will not be sent to an unrelated port.
779		845
780	=item * Erlang uses unprotected connections, AEMP uses secure	846	=item * Erlang uses unprotected connections, AEMP uses secure
781	authentication and can use TLS.	847	authentication and can use TLS.
782		848
783	AEMP can use a proven protocol - SSL/TLS - to protect connections and	849	AEMP can use a proven protocol - TLS - to protect connections and
784	securely authenticate nodes.	850	securely authenticate nodes.
785		851
786	=item * The AEMP protocol is optimised for both text-based and binary	852	=item * The AEMP protocol is optimised for both text-based and binary
787	communications.	853	communications.
788		854
789	The AEMP protocol, unlike the Erlang protocol, supports both	855	The AEMP protocol, unlike the Erlang protocol, supports both programming
790	language-independent text-only protocols (good for debugging) and binary,	856	language independent text-only protocols (good for debugging) and binary,
791	language-specific serialisers (e.g. Storable).	857	language-specific serialisers (e.g. Storable). By default, unless TLS is
		858	used, the protocol is actually completely text-based.
792		859
793	It has also been carefully designed to be implementable in other languages	860	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	861	with a minimum of work while gracefully degrading functionality to make the
795	protocol simple.	862	protocol simple.
796		863
797	=item * AEMP has more flexible monitoring options than Erlang.	864	=item * AEMP has more flexible monitoring options than Erlang.
798		865
799	In Erlang, you can chose to receive I<all> exit signals as messages	866	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	869	Erlang, as one can choose between automatic kill, exit message or callback
803	on a per-process basis.	870	on a per-process basis.
804		871
805	=item * Erlang tries to hide remote/local connections, AEMP does not.	872	=item * Erlang tries to hide remote/local connections, AEMP does not.
806		873
807	Monitoring in Erlang is not an indicator of process death/crashes,	874	Monitoring in Erlang is not an indicator of process death/crashes, in the
808	as linking is (except linking is unreliable in Erlang).	875	same way as linking is (except linking is unreliable in Erlang).
809		876
810	In AEMP, you don't "look up" registered port names or send to named ports	877	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	878	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	879	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	880	remote port. Since both monitors are local to the node, they are much more
814	more reliable.	881	reliable (no need for C<spawn_link>).
815		882
816	This also saves round-trips and avoids sending messages to the wrong port	883	This also saves round-trips and avoids sending messages to the wrong port
817	(hard to do in Erlang).	884	(hard to do in Erlang).
818		885
819	=back	886	=back
820		887
821	=head1 RATIONALE	888	=head1 RATIONALE
822		889
823	=over 4	890	=over 4
824		891
825	=item Why strings for ports and noderefs, why not objects?	892	=item Why strings for port and node IDs, why not objects?
826		893
827	We considered "objects", but found that the actual number of methods	894	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	895	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	896	the network frequently, the serialising/deserialising would add lots of
830	overhead, as well as having to keep a proxy object.	897	overhead, as well as having to keep a proxy object everywhere.
831		898
832	Strings can easily be printed, easily serialised etc. and need no special	899	Strings can easily be printed, easily serialised etc. and need no special
833	procedures to be "valid".	900	procedures to be "valid".
834		901
835	And a a miniport consists of a single closure stored in a global hash - it	902	And as a result, a miniport consists of a single closure stored in a
836	can't become much cheaper.	903	global hash - it can't become much cheaper.
837		904
838	=item Why favour JSON, why not real serialising format such as Storable?	905	=item Why favour JSON, why not a real serialising format such as Storable?
839		906
840	In fact, any AnyEvent::MP node will happily accept Storable as framing	907	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	908	format, but currently there is no way to make a node use Storable by
842	default.	909	default (although all nodes will accept it).
843		910
844	The default framing protocol is JSON because a) JSON::XS is many times	911	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	912	faster for small messages and b) most importantly, after years of
846	experience we found that object serialisation is causing more problems	913	experience we found that object serialisation is causing more problems
847	than it gains: Just like function calls, objects simply do not travel	914	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	915	easily over the network, mostly because they will always be a copy, so you
849	always have to re-think your design.	916	always have to re-think your design.
850		917
851	Keeping your messages simple, concentrating on data structures rather than	918	Keeping your messages simple, concentrating on data structures rather than
852	objects, will keep your messages clean, tidy and efficient.	919	objects, will keep your messages clean, tidy and efficient.
853		920
854	=back	921	=back
855		922
856	=head1 SEE ALSO	923	=head1 SEE ALSO
857		924
		925	L<AnyEvent::MP::Intro> - a gentle introduction.
		926
		927	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		928
		929	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		930	your applications.
		931
		932	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		933	all nodes.
		934
858	L<AnyEvent>.	935	L<AnyEvent>.
859		936
860	=head1 AUTHOR	937	=head1 AUTHOR
861		938
862	Marc Lehmann <schmorp@schmorp.de>	939	Marc Lehmann <schmorp@schmorp.de>

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC vs. Revision 1.100 by root, Fri Oct 2 20:41:56 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC vs.
Revision 1.100 by root, Fri Oct 2 20:41:56 2009 UTC