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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs.
Revision 1.88 by root, Fri Sep 11 15:02:17 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
15	# initialise the node so it can send/receive messages	14	# initialise the node so it can send/receive messages
16	initialise_node;	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44	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.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 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 send to ports will not be queued, regardless of	68	some messages. Messages send to ports will not be queued, regardless of
74	anything was listening for them or not.	69	anything was listening for them or not.
75		70
76	=item port ID - C<noderef#portname>	71	=item port ID - C<nodeid#portname>
77		72
78	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
79	separator, and a port name (a printable string of unspecified format). An	74	separator, and a port name (a printable string of unspecified format).
80	exception is the the node port, whose ID is identical to its node
81	reference.
82		75
83	=item node	76	=item node
84		77
85	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,
86	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
87	ports.	80	ports.
88		81
89	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
90	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
91	from any other node).	84	currently.
92		85
93	=item node ID - C<[a-za-Z0-9_\-.:]+>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
94		87
95	A node ID is a string that uniquely identifies the node within a	88	A node ID is a string that uniquely identifies the node within a
96	network. Depending on the configuration used, node IDs can look like a	89	network. Depending on the configuration used, node IDs can look like a
97	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	90	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
98	doesn't interpret node IDs in any way.	91	doesn't interpret node IDs in any way.
…		…
102	Nodes can only talk to each other by creating some kind of connection to	95	Nodes can only talk to each other by creating some kind of connection to
103	each other. To do this, nodes should listen on one or more local transport	96	each other. To do this, nodes should listen on one or more local transport
104	endpoints - binds. Currently, only standard C<ip:port> specifications can	97	endpoints - binds. Currently, only standard C<ip:port> specifications can
105	be used, which specify TCP ports to listen on.	98	be used, which specify TCP ports to listen on.
106		99
107	=item seeds - C<host:port>	100	=item seed nodes
108		101
109	When a node starts, it knows nothing about the network. To teach the node	102	When a node starts, it knows nothing about the network. To teach the node
110	about the network it first has to contact some other node within the	103	about the network it first has to contact some other node within the
111	network. This node is called a seed.	104	network. This node is called a seed.
112		105
113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	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	are expected to be long-running, and at least one of those should always	114	Seed nodes are expected to be long-running, and at least one seed node
115	be available. When nodes run out of connections (e.g. due to a network	115	should always be available. They should also be relatively responsive - a
116	error), they try to re-establish connections to some seednodes again to	116	seed node that blocks for long periods will slow down everybody else.
117	join the network.	117
		118	=item seeds - C<host:port>
		119
		120	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		121	TCP port) of nodes thta should be used as seed nodes.
		122
		123	The nodes listening on those endpoints are expected to be long-running,
		124	and at least one of those should always be available. When nodes run out
		125	of connections (e.g. due to a network error), they try to re-establish
		126	connections to some seednodes again to join the network.
118		127
119	=back	128	=back
120		129
121	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
122		131
…		…
138		147
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	148	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
140		149
141	our @EXPORT = qw(	150	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	151	NODE $NODE *SELF node_of after
143	resolve_node initialise_node	152	configure
144	snd rcv mon mon_guard kil reg psub spawn	153	snd rcv mon mon_guard kil reg psub spawn cal
145	port	154	port
146	);	155	);
147		156
148	our $SELF;	157	our $SELF;
149		158
…		…
153	kil $SELF, die => $msg;	162	kil $SELF, die => $msg;
154	}	163	}
155		164
156	=item $thisnode = NODE / $NODE	165	=item $thisnode = NODE / $NODE
157		166
158	The C<NODE> function returns, and the C<$NODE> variable contains the node	167	The C<NODE> function returns, and the C<$NODE> variable contains, the node
159	ID of the node running in the current process. This value is initialised by	168	ID of the node running in the current process. This value is initialised by
160	a call to C<initialise_node>.	169	a call to C<configure>.
161		170
162	=item $nodeid = node_of $port	171	=item $nodeid = node_of $port
163		172
164	Extracts and returns the node ID part from a port ID or a node ID.	173	Extracts and returns the node ID from a port ID or a node ID.
165		174
166	=item initialise_node $profile_name	175	=item configure $profile, key => value...
		176
		177	=item configure key => value...
167		178
168	Before a node can talk to other nodes on the network (i.e. enter	179	Before a node can talk to other nodes on the network (i.e. enter
169	"distributed mode") it has to initialise itself - the minimum a node needs	180	"distributed mode") it has to configure itself - the minimum a node needs
170	to know is its own name, and optionally it should know the addresses of	181	to know is its own name, and optionally it should know the addresses of
171	some other nodes in the network to discover other nodes.	182	some other nodes in the network to discover other nodes.
172		183
173	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
174	never) before calling other AnyEvent::MP functions.	185	never) before calling other AnyEvent::MP functions.
175		186
176	The first argument is a profile name. If it is C<undef> or missing, then	187	=over 4
177	the current nodename will be used instead (i.e. F<uname -n>).
178		188
		189	=item step 1, gathering configuration from profiles
		190
179	The function then looks up the profile in the aemp configuration (see the	191	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility).	192	L<aemp> commandline utility). The profile name can be specified via the
		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.
		195
		196	The profile data is then gathered as follows:
		197
		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).
		203
		204	That means that the values specified in the profile have highest priority
		205	and the values specified directly via C<configure> have lowest priority,
		206	and can only be used to specify defaults.
181		207
182	If the profile specifies a node ID, then this will become the node ID of	208	If the profile specifies a node ID, then this will become the node ID of
183	this process. If not, then the profile name will be used as node ID. The	209	this process. If not, then the profile name will be used as node ID. The
184	special node ID of C<anon/> will be replaced by a random node ID.	210	special node ID of C<anon/> will be replaced by a random node ID.
		211
		212	=item step 2, bind listener sockets
185		213
186	The next step is to look up the binds in the profile, followed by binding	214	The next step is to look up the binds in the profile, followed by binding
187	aemp protocol listeners on all binds specified (it is possible and valid	215	aemp protocol listeners on all binds specified (it is possible and valid
188	to have no binds, meaning that the node cannot be contacted form the	216	to have no binds, meaning that the node cannot be contacted form the
189	outside. This means the node cannot talk to other nodes that also have no	217	outside. This means the node cannot talk to other nodes that also have no
190	binds, but it can still talk to all "normal" nodes).	218	binds, but it can still talk to all "normal" nodes).
191		219
192	If the profile does not specify a binds list, then the node ID will be	220	If the profile does not specify a binds list, then a default of C<*> is
193	treated as if it were of the form C<host:port>, which will be resolved and	221	used, meaning the node will bind on a dynamically-assigned port on every
194	used as binds list.	222	local IP address it finds.
195		223
		224	=item step 3, connect to seed nodes
		225
196	Lastly, the seeds list from the profile is passed to the	226	As the last step, the seeds list from the profile is passed to the
197	L<AnyEvent::MP::Global> module, which will then use it to keep	227	L<AnyEvent::MP::Global> module, which will then use it to keep
198	connectivity with at least on of those seed nodes at any point in time.	228	connectivity with at least one node at any point in time.
199		229
200	Example: become a distributed node listening on the guessed noderef, or	230	=back
201	the one specified via C<aemp> for the current node. This should be the	231
		232	Example: become a distributed node using the local node name as profile.
202	most common form of invocation for "daemon"-type nodes.	233	This should be the most common form of invocation for "daemon"-type nodes.
203		234
204	initialise_node;	235	configure
205		236
206	Example: become an anonymous node. This form is often used for commandline	237	Example: become an anonymous node. This form is often used for commandline
207	clients.	238	clients.
208		239
209	initialise_node "anon/";	240	configure nodeid => "anon/";
210		241
211	Example: become a distributed node. If there is no profile of the given	242	Example: configure a node using a profile called seed, which si suitable
212	name, or no binds list was specified, resolve C<localhost:4044> and bind	243	for a seed node as it binds on all local addresses on a fixed port (4040,
213	on the resulting addresses.	244	customary for aemp).
214		245
215	initialise_node "localhost:4044";	246	# use the aemp commandline utility
		247	# aemp profile seed nodeid anon/ binds '*:4040'
		248
		249	# then use it
		250	configure profile => "seed";
		251
		252	# or simply use aemp from the shell again:
		253	# aemp run profile seed
		254
		255	# or provide a nicer-to-remember nodeid
		256	# aemp run profile seed nodeid "$(hostname)"
216		257
217	=item $SELF	258	=item $SELF
218		259
219	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
220	blocks.	261	blocks.
221		262
222	=item SELF, %SELF, @SELF...	263	=item *SELF, SELF, %SELF, @SELF...
223		264
224	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
225	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols named C<SELF> are exported by this
226	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
227		268
228	=item snd $port, type => @data	269	=item snd $port, type => @data
229		270
230	=item snd $port, @msg	271	=item snd $port, @msg
231		272
232	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
233	a local or a remote port, and must be a port ID.	274	local or a remote port, and must be a port ID.
234		275
235	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
236	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
237	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.
238		280
239	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
240	function: modifying any argument is not allowed and can cause many	282	function: modifying any argument (or values referenced by them) is
241	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.
242		287
243	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
244	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
245	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
246	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
247	node, anything can be passed.	292	node, anything can be passed. Best rely only on the common denominator of
		293	these.
248		294
249	=item $local_port = port	295	=item $local_port = port
250		296
251	Create a new local port object and returns its port ID. Initially it has	297	Create a new local port object and returns its port ID. Initially it has
252	no callbacks set and will throw an error when it receives messages.	298	no callbacks set and will throw an error when it receives messages.
…		…
337		383
338	=cut	384	=cut
339		385
340	sub rcv($@) {	386	sub rcv($@) {
341	my $port = shift;	387	my $port = shift;
342	my ($noderef, $portid) = split /#/, $port, 2;	388	my ($nodeid, $portid) = split /#/, $port, 2;
343		389
344	$NODE{$noderef} == $NODE{""}	390	$NODE{$nodeid} == $NODE{""}
345	or Carp::croak "$port: rcv can only be called on local ports, caught";	391	or Carp::croak "$port: rcv can only be called on local ports, caught";
346		392
347	while (@_) {	393	while (@_) {
348	if (ref $_[0]) {	394	if (ref $_[0]) {
349	if (my $self = $PORT_DATA{$portid}) {	395	if (my $self = $PORT_DATA{$portid}) {
…		…
428	$res	474	$res
429	}	475	}
430	}	476	}
431	}	477	}
432		478
433	=item $guard = mon $port, $cb->(@reason)	479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
434		480
435	=item $guard = mon $port, $rcvport	481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
436		482
437	=item $guard = mon $port	483	=item $guard = mon $port # kill $SELF when $port dies
438		484
439	=item $guard = mon $port, $rcvport, @msg	485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
440		486
441	Monitor the given port and do something when the port is killed or	487	Monitor the given port and do something when the port is killed or
442	messages to it were lost, and optionally return a guard that can be used	488	messages to it were lost, and optionally return a guard that can be used
443	to stop monitoring again.	489	to stop monitoring again.
444
445	C<mon> effectively guarantees that, in the absence of hardware failures,
446	that after starting the monitor, either all messages sent to the port
447	will arrive, or the monitoring action will be invoked after possible
448	message loss has been detected. No messages will be lost "in between"
449	(after the first lost message no further messages will be received by the
450	port). After the monitoring action was invoked, further messages might get
451	delivered again.
452
453	Note that monitoring-actions are one-shot: once released, they are removed
454	and will not trigger again.
455		490
456	In the first form (callback), the callback is simply called with any	491	In the first form (callback), the callback is simply called with any
457	number of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
458	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
459	C<eval> if unsure.	494	C<eval> if unsure.
460		495
461	In the second form (another port given), the other port (C<$rcvport>)	496	In the second form (another port given), the other port (C<$rcvport>)
462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
463	"normal" kils nothing happens, while under all other conditions, the other	498	"normal" kils nothing happens, while under all other conditions, the other
464	port is killed with the same reason.	499	port is killed with the same reason.
465		500
466	The third form (kill self) is the same as the second form, except that	501	The third form (kill self) is the same as the second form, except that
467	C<$rvport> defaults to C<$SELF>.	502	C<$rvport> defaults to C<$SELF>.
468		503
469	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
470	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.
471		509
472	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
473	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
474	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
475	even monitoring requests can get lost (for exmaple, when the connection	513	even monitoring requests can get lost (for example, when the connection
476	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
477	these problems do not exist.	515	these problems do not exist.
478		516
		517	C<mon> effectively guarantees that, in the absence of hardware failures,
		518	after starting the monitor, either all messages sent to the port will
		519	arrive, or the monitoring action will be invoked after possible message
		520	loss has been detected. No messages will be lost "in between" (after
		521	the first lost message no further messages will be received by the
		522	port). After the monitoring action was invoked, further messages might get
		523	delivered again.
		524
		525	Inter-host-connection timeouts and monitoring depend on the transport
		526	used. The only transport currently implemented is TCP, and AnyEvent::MP
		527	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		528	non-idle connection, and usually around two hours for idle conenctions).
		529
		530	This means that monitoring is good for program errors and cleaning up
		531	stuff eventually, but they are no replacement for a timeout when you need
		532	to ensure some maximum latency.
		533
479	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
480		535
481	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
482		537
483	Example: kill ourselves when C<$port> is killed abnormally.	538	Example: kill ourselves when C<$port> is killed abnormally.
…		…
489	mon $port, $self => "restart";	544	mon $port, $self => "restart";
490		545
491	=cut	546	=cut
492		547
493	sub mon {	548	sub mon {
494	my ($noderef, $port) = split /#/, shift, 2;	549	my ($nodeid, $port) = split /#/, shift, 2;
495		550
496	my $node = $NODE{$noderef} \|\| add_node $noderef;	551	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
497		552
498	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,';
499		554
500	unless (ref $cb) {	555	unless (ref $cb) {
501	if (@_) {	556	if (@_) {
…		…
521	is killed, the references will be freed.	576	is killed, the references will be freed.
522		577
523	Optionally returns a guard that will stop the monitoring.	578	Optionally returns a guard that will stop the monitoring.
524		579
525	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
526	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>):
527		582
528	$port->rcv (start => sub {	583	$port->rcv (start => sub {
529	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	584	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
530	undef $timer if 0.9 < rand;	585	undef $timer if 0.9 < rand;
531	});	586	});
532	});	587	});
533		588
534	=cut	589	=cut
…		…
543		598
544	=item kil $port[, @reason]	599	=item kil $port[, @reason]
545		600
546	Kill the specified port with the given C<@reason>.	601	Kill the specified port with the given C<@reason>.
547		602
548	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
549	ports will not be kileld, or even notified).	604	monitoring other ports will not necessarily die because a port dies
		605	"normally").
550		606
551	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
552	C<mon>, see below).	608	C<mon>, see above).
553		609
554	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
555	will be reported as reason C<< die => $@ >>.	611	will be reported as reason C<< die => $@ >>.
556		612
557	Transport/communication errors are reported as C<< transport_error =>	613	Transport/communication errors are reported as C<< transport_error =>
…		…
562	=item $port = spawn $node, $initfunc[, @initdata]	618	=item $port = spawn $node, $initfunc[, @initdata]
563		619
564	Creates a port on the node C<$node> (which can also be a port ID, in which	620	Creates a port on the node C<$node> (which can also be a port ID, in which
565	case it's the node where that port resides).	621	case it's the node where that port resides).
566		622
567	The port ID of the newly created port is return immediately, and it is	623	The port ID of the newly created port is returned immediately, and it is
568	permissible to immediately start sending messages or monitor the port.	624	possible to immediately start sending messages or to monitor the port.
569		625
570	After the port has been created, the init function is	626	After the port has been created, the init function is called on the remote
571	called. This function must be a fully-qualified function name	627	node, in the same context as a C<rcv> callback. This function must be a
572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	628	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
573	program, use C<::name>.	629	specify a function in the main program, use C<::name>.
574		630
575	If the function doesn't exist, then the node tries to C<require>	631	If the function doesn't exist, then the node tries to C<require>
576	the package, then the package above the package and so on (e.g.	632	the package, then the package above the package and so on (e.g.
577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	633	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
578	exists or it runs out of package names.	634	exists or it runs out of package names.
579		635
580	The init function is then called with the newly-created port as context	636	The init function is then called with the newly-created port as context
581	object (C<$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.
582		640
583	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
584	in the init function, monitor the original port. This two-way monitoring	642	port, and in the remote init function, immediately monitor the passed
585	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<$initfunc> has no visible effects on the
		647	caller before C<spawn> returns (by delaying invocation when spawn is
		648	called for the local node).
586		649
587	Example: spawn a chat server port on C<$othernode>.	650	Example: spawn a chat server port on C<$othernode>.
588		651
589	# this node, executed from within a port context:	652	# this node, executed from within a port context:
590	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
605		668
606	sub _spawn {	669	sub _spawn {
607	my $port = shift;	670	my $port = shift;
608	my $init = shift;	671	my $init = shift;
609		672
		673	# rcv will create the actual port
610	local $SELF = "$NODE#$port";	674	local $SELF = "$NODE#$port";
611	eval {	675	eval {
612	&{ load_func $init }	676	&{ load_func $init }
613	};	677	};
614	_self_die if $@;	678	_self_die if $@;
615	}	679	}
616		680
617	sub spawn(@) {	681	sub spawn(@) {
618	my ($noderef, undef) = split /#/, shift, 2;	682	my ($nodeid, undef) = split /#/, shift, 2;
619		683
620	my $id = "$RUNIQ." . $ID++;	684	my $id = "$RUNIQ." . $ID++;
621		685
622	$_[0] =~ /::/	686	$_[0] =~ /::/
623	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";
624		688
625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
626		690
627	"$noderef#$id"	691	"$nodeid#$id"
628	}	692	}
629		693
630	=item after $timeout, @msg	694	=item after $timeout, @msg
631		695
632	=item after $timeout, $callback	696	=item after $timeout, $callback
633		697
634	Either sends the given message, or call the given callback, after the	698	Either sends the given message, or call the given callback, after the
635	specified number of seconds.	699	specified number of seconds.
636		700
637	This is simply a utility function that come sin handy at times.	701	This is simply a utility function that comes in handy at times - the
		702	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		703	so it may go away in the future.
638		704
639	=cut	705	=cut
640		706
641	sub after($@) {	707	sub after($@) {
642	my ($timeout, @action) = @_;	708	my ($timeout, @action) = @_;
…		…
647	? $action[0]()	713	? $action[0]()
648	: snd @action;	714	: snd @action;
649	};	715	};
650	}	716	}
651		717
		718	=item cal $port, @msg, $callback[, $timeout]
		719
		720	A simple form of RPC - sends a message to the given C<$port> with the
		721	given contents (C<@msg>), but adds a reply port to the message.
		722
		723	The reply port is created temporarily just for the purpose of receiving
		724	the reply, and will be C<kil>ed when no longer needed.
		725
		726	A reply message sent to the port is passed to the C<$callback> as-is.
		727
		728	If an optional time-out (in seconds) is given and it is not C<undef>,
		729	then the callback will be called without any arguments after the time-out
		730	elapsed and the port is C<kil>ed.
		731
		732	If no time-out is given, then the local port will monitor the remote port
		733	instead, so it eventually gets cleaned-up.
		734
		735	Currently this function returns the temporary port, but this "feature"
		736	might go in future versions unless you can make a convincing case that
		737	this is indeed useful for something.
		738
		739	=cut
		740
		741	sub cal(@) {
		742	my $timeout = ref $_[-1] ? undef : pop;
		743	my $cb = pop;
		744
		745	my $port = port {
		746	undef $timeout;
		747	kil $SELF;
		748	&$cb;
		749	};
		750
		751	if (defined $timeout) {
		752	$timeout = AE::timer $timeout, 0, sub {
		753	undef $timeout;
		754	kil $port;
		755	$cb->();
		756	};
		757	} else {
		758	mon $_[0], sub {
		759	kil $port;
		760	$cb->();
		761	};
		762	}
		763
		764	push @_, $port;
		765	&snd;
		766
		767	$port
		768	}
		769
652	=back	770	=back
653		771
654	=head1 AnyEvent::MP vs. Distributed Erlang	772	=head1 AnyEvent::MP vs. Distributed Erlang
655		773
656	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
…		…
669		787
670	=item * Node IDs are arbitrary strings in AEMP.	788	=item * Node IDs are arbitrary strings in AEMP.
671		789
672	Erlang relies on special naming and DNS to work everywhere in the same	790	Erlang relies on special naming and DNS to work everywhere in the same
673	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	791	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
674	configuraiton or DNS), but will otherwise discover other odes itself.	792	configuration or DNS), but will otherwise discover other odes itself.
675		793
676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	794	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
677	uses "local ports are like remote ports".	795	uses "local ports are like remote ports".
678		796
679	The failure modes for local ports are quite different (runtime errors	797	The failure modes for local ports are quite different (runtime errors
…		…
692		810
693	Erlang uses processes that selectively receive messages, and therefore	811	Erlang uses processes that selectively receive messages, and therefore
694	needs a queue. AEMP is event based, queuing messages would serve no	812	needs a queue. AEMP is event based, queuing messages would serve no
695	useful purpose. For the same reason the pattern-matching abilities of	813	useful purpose. For the same reason the pattern-matching abilities of
696	AnyEvent::MP are more limited, as there is little need to be able to	814	AnyEvent::MP are more limited, as there is little need to be able to
697	filter messages without dequeing them.	815	filter messages without dequeuing them.
698		816
699	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	817	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
700		818
701	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	819	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
702		820
…		…
708		826
709	Erlang makes few guarantees on messages delivery - messages can get lost	827	Erlang makes few guarantees on messages delivery - messages can get lost
710	without any of the processes realising it (i.e. you send messages a, b,	828	without any of the processes realising it (i.e. you send messages a, b,
711	and c, and the other side only receives messages a and c).	829	and c, and the other side only receives messages a and c).
712		830
713	AEMP guarantees correct ordering, and the guarantee that there are no	831	AEMP guarantees correct ordering, and the guarantee that after one message
714	holes in the message sequence.	832	is lost, all following ones sent to the same port are lost as well, until
715		833	monitoring raises an error, so there are no silent "holes" in the message
716	=item * In Erlang, processes can be declared dead and later be found to be	834	sequence.
717	alive.
718
719	In Erlang it can happen that a monitored process is declared dead and
720	linked processes get killed, but later it turns out that the process is
721	still alive - and can receive messages.
722
723	In AEMP, when port monitoring detects a port as dead, then that port will
724	eventually be killed - it cannot happen that a node detects a port as dead
725	and then later sends messages to it, finding it is still alive.
726		835
727	=item * Erlang can send messages to the wrong port, AEMP does not.	836	=item * Erlang can send messages to the wrong port, AEMP does not.
728		837
729	In Erlang it is quite likely that a node that restarts reuses a process ID	838	In Erlang it is quite likely that a node that restarts reuses a process ID
730	known to other nodes for a completely different process, causing messages	839	known to other nodes for a completely different process, causing messages
…		…
734	around in the network will not be sent to an unrelated port.	843	around in the network will not be sent to an unrelated port.
735		844
736	=item * Erlang uses unprotected connections, AEMP uses secure	845	=item * Erlang uses unprotected connections, AEMP uses secure
737	authentication and can use TLS.	846	authentication and can use TLS.
738		847
739	AEMP can use a proven protocol - SSL/TLS - to protect connections and	848	AEMP can use a proven protocol - TLS - to protect connections and
740	securely authenticate nodes.	849	securely authenticate nodes.
741		850
742	=item * The AEMP protocol is optimised for both text-based and binary	851	=item * The AEMP protocol is optimised for both text-based and binary
743	communications.	852	communications.
744		853
745	The AEMP protocol, unlike the Erlang protocol, supports both	854	The AEMP protocol, unlike the Erlang protocol, supports both programming
746	language-independent text-only protocols (good for debugging) and binary,	855	language independent text-only protocols (good for debugging) and binary,
747	language-specific serialisers (e.g. Storable).	856	language-specific serialisers (e.g. Storable). By default, unless TLS is
		857	used, the protocol is actually completely text-based.
748		858
749	It has also been carefully designed to be implementable in other languages	859	It has also been carefully designed to be implementable in other languages
750	with a minimum of work while gracefully degrading fucntionality to make the	860	with a minimum of work while gracefully degrading functionality to make the
751	protocol simple.	861	protocol simple.
752		862
753	=item * AEMP has more flexible monitoring options than Erlang.	863	=item * AEMP has more flexible monitoring options than Erlang.
754		864
755	In Erlang, you can chose to receive I<all> exit signals as messages	865	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
758	Erlang, as one can choose between automatic kill, exit message or callback	868	Erlang, as one can choose between automatic kill, exit message or callback
759	on a per-process basis.	869	on a per-process basis.
760		870
761	=item * Erlang tries to hide remote/local connections, AEMP does not.	871	=item * Erlang tries to hide remote/local connections, AEMP does not.
762		872
763	Monitoring in Erlang is not an indicator of process death/crashes,	873	Monitoring in Erlang is not an indicator of process death/crashes, in the
764	as linking is (except linking is unreliable in Erlang).	874	same way as linking is (except linking is unreliable in Erlang).
765		875
766	In AEMP, you don't "look up" registered port names or send to named ports	876	In AEMP, you don't "look up" registered port names or send to named ports
767	that might or might not be persistent. Instead, you normally spawn a port	877	that might or might not be persistent. Instead, you normally spawn a port
768	on the remote node. The init function monitors the you, and you monitor	878	on the remote node. The init function monitors you, and you monitor the
769	the remote port. Since both monitors are local to the node, they are much	879	remote port. Since both monitors are local to the node, they are much more
770	more reliable.	880	reliable (no need for C<spawn_link>).
771		881
772	This also saves round-trips and avoids sending messages to the wrong port	882	This also saves round-trips and avoids sending messages to the wrong port
773	(hard to do in Erlang).	883	(hard to do in Erlang).
774		884
775	=back	885	=back
776		886
777	=head1 RATIONALE	887	=head1 RATIONALE
778		888
779	=over 4	889	=over 4
780		890
781	=item Why strings for ports and noderefs, why not objects?	891	=item Why strings for port and node IDs, why not objects?
782		892
783	We considered "objects", but found that the actual number of methods	893	We considered "objects", but found that the actual number of methods
784	thatc an be called are very low. Since port IDs and noderefs travel over	894	that can be called are quite low. Since port and node IDs travel over
785	the network frequently, the serialising/deserialising would add lots of	895	the network frequently, the serialising/deserialising would add lots of
786	overhead, as well as having to keep a proxy object.	896	overhead, as well as having to keep a proxy object everywhere.
787		897
788	Strings can easily be printed, easily serialised etc. and need no special	898	Strings can easily be printed, easily serialised etc. and need no special
789	procedures to be "valid".	899	procedures to be "valid".
790		900
791	And a a miniport consists of a single closure stored in a global hash - it	901	And as a result, a miniport consists of a single closure stored in a
792	can't become much cheaper.	902	global hash - it can't become much cheaper.
793		903
794	=item Why favour JSON, why not real serialising format such as Storable?	904	=item Why favour JSON, why not a real serialising format such as Storable?
795		905
796	In fact, any AnyEvent::MP node will happily accept Storable as framing	906	In fact, any AnyEvent::MP node will happily accept Storable as framing
797	format, but currently there is no way to make a node use Storable by	907	format, but currently there is no way to make a node use Storable by
798	default.	908	default (although all nodes will accept it).
799		909
800	The default framing protocol is JSON because a) JSON::XS is many times	910	The default framing protocol is JSON because a) JSON::XS is many times
801	faster for small messages and b) most importantly, after years of	911	faster for small messages and b) most importantly, after years of
802	experience we found that object serialisation is causing more problems	912	experience we found that object serialisation is causing more problems
803	than it gains: Just like function calls, objects simply do not travel	913	than it solves: Just like function calls, objects simply do not travel
804	easily over the network, mostly because they will always be a copy, so you	914	easily over the network, mostly because they will always be a copy, so you
805	always have to re-think your design.	915	always have to re-think your design.
806		916
807	Keeping your messages simple, concentrating on data structures rather than	917	Keeping your messages simple, concentrating on data structures rather than
808	objects, will keep your messages clean, tidy and efficient.	918	objects, will keep your messages clean, tidy and efficient.
809		919
810	=back	920	=back
811		921
812	=head1 SEE ALSO	922	=head1 SEE ALSO
813		923
		924	L<AnyEvent::MP::Intro> - a gentle introduction.
		925
		926	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		927
		928	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		929	your applications.
		930
		931	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		932	all nodes.
		933
814	L<AnyEvent>.	934	L<AnyEvent>.
815		935
816	=head1 AUTHOR	936	=head1 AUTHOR
817		937
818	Marc Lehmann <schmorp@schmorp.de>	938	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs. Revision 1.88 by root, Fri Sep 11 15:02:17 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC vs.
Revision 1.88 by root, Fri Sep 11 15:02:17 2009 UTC