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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs.
Revision 1.79 by root, Fri Sep 4 21:52:09 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
…		…
40		39
41	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
42		41
43	bin/aemp - stable.	42	bin/aemp - stable.
44	AnyEvent::MP - stable API, should work.	43	AnyEvent::MP - stable API, should work.
45	AnyEvent::MP::Intro - uptodate, but incomplete.	44	AnyEvent::MP::Intro - explains most concepts.
46	AnyEvent::MP::Kernel - mostly stable.	45	AnyEvent::MP::Kernel - mostly stable.
47	AnyEvent::MP::Global - stable API, protocol not yet final.	46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
48		47
49	stay tuned.	48	stay tuned.
50		49
51	=head1 DESCRIPTION	50	=head1 DESCRIPTION
52		51
53	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
54		53
…		…
56	on the same or other hosts, and you can supervise entities remotely.	55	on the same or other hosts, and you can supervise entities remotely.
57		56
58	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
59	manual page and the examples under F<eg/>.	58	manual page and the examples under F<eg/>.
60		59
61	At the moment, this module family is a bit underdocumented.
62
63	=head1 CONCEPTS	60	=head1 CONCEPTS
64		61
65	=over 4	62	=over 4
66		63
67	=item port	64	=item port
68		65
69	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
70		68
71	Ports allow you to register C<rcv> handlers that can match all or just	69	Ports allow you to register C<rcv> handlers that can match all or just
72	some messages. Messages send to ports will not be queued, regardless of	70	some messages. Messages send to ports will not be queued, regardless of
73	anything was listening for them or not.	71	anything was listening for them or not.
74		72
…		…
138		136
139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
140		138
141	our @EXPORT = qw(	139	our @EXPORT = qw(
142	NODE $NODE *SELF node_of after	140	NODE $NODE *SELF node_of after
143	initialise_node	141	configure
144	snd rcv mon mon_guard kil reg psub spawn	142	snd rcv mon mon_guard kil reg psub spawn
145	port	143	port
146	);	144	);
147		145
148	our $SELF;	146	our $SELF;
…		…
155		153
156	=item $thisnode = NODE / $NODE	154	=item $thisnode = NODE / $NODE
157		155
158	The C<NODE> function returns, and the C<$NODE> variable contains, the node	156	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	157	ID of the node running in the current process. This value is initialised by
160	a call to C<initialise_node>.	158	a call to C<configure>.
161		159
162	=item $nodeid = node_of $port	160	=item $nodeid = node_of $port
163		161
164	Extracts and returns the node ID from a port ID or a node ID.	162	Extracts and returns the node ID from a port ID or a node ID.
165		163
166	=item initialise_node $profile_name, key => value...	164	=item configure $profile, key => value...
		165
		166	=item configure key => value...
167		167
168	Before a node can talk to other nodes on the network (i.e. enter	168	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	169	"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	170	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.	171	some other nodes in the network to discover other nodes.
172		172
173	This function initialises a node - it must be called exactly once (or	173	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
175		175
176	The first argument is a profile name. If it is C<undef> or missing, then	176	=over 4
177	the current nodename will be used instead (i.e. F<uname -n>).
178		177
		178	=item step 1, gathering configuration from profiles
		179
179	The function first looks up the profile in the aemp configuration (see the	180	The function first looks up a profile in the aemp configuration (see the
180	L<aemp> commandline utility). the profile is calculated as follows:	181	L<aemp> commandline utility). The profile name can be specified via the
		182	named C<profile> parameter or can simply be the first parameter). If it is
		183	missing, then the nodename (F<uname -n>) will be used as profile name.
181		184
		185	The profile data is then gathered as follows:
		186
182	First, all remaining key => value pairs (all of which are conviniently	187	First, all remaining key => value pairs (all of which are conveniently
183	undocumented at the moment) will be used. Then they will be overwritten by	188	undocumented at the moment) will be interpreted as configuration
184	any values specified in the global default configuration (see the F<aemp>	189	data. Then they will be overwritten by any values specified in the global
185	utility), then the chain of profiles selected, if any. That means that	190	default configuration (see the F<aemp> utility), then the chain of
		191	profiles chosen by the profile name (and any C<parent> attributes).
		192
186	the values specified in the profile have highest priority and the values	193	That means that the values specified in the profile have highest priority
187	specified via C<initialise_node> have lowest priority.	194	and the values specified directly via C<configure> have lowest priority,
		195	and can only be used to specify defaults.
188		196
189	If the profile specifies a node ID, then this will become the node ID of	197	If the profile specifies a node ID, then this will become the node ID of
190	this process. If not, then the profile name will be used as node ID. The	198	this process. If not, then the profile name will be used as node ID. The
191	special node ID of C<anon/> will be replaced by a random node ID.	199	special node ID of C<anon/> will be replaced by a random node ID.
		200
		201	=item step 2, bind listener sockets
192		202
193	The next step is to look up the binds in the profile, followed by binding	203	The next step is to look up the binds in the profile, followed by binding
194	aemp protocol listeners on all binds specified (it is possible and valid	204	aemp protocol listeners on all binds specified (it is possible and valid
195	to have no binds, meaning that the node cannot be contacted form the	205	to have no binds, meaning that the node cannot be contacted form the
196	outside. This means the node cannot talk to other nodes that also have no	206	outside. This means the node cannot talk to other nodes that also have no
197	binds, but it can still talk to all "normal" nodes).	207	binds, but it can still talk to all "normal" nodes).
198		208
199	If the profile does not specify a binds list, then a default of C<*> is	209	If the profile does not specify a binds list, then a default of C<*> is
200	used.	210	used, meaning the node will bind on a dynamically-assigned port on every
		211	local IP address it finds.
201		212
		213	=item step 3, connect to seed nodes
		214
202	Lastly, the seeds list from the profile is passed to the	215	As the last step, the seeds list from the profile is passed to the
203	L<AnyEvent::MP::Global> module, which will then use it to keep	216	L<AnyEvent::MP::Global> module, which will then use it to keep
204	connectivity with at least on of those seed nodes at any point in time.	217	connectivity with at least one node at any point in time.
205		218
206	Example: become a distributed node listening on the guessed noderef, or	219	=back
207	the one specified via C<aemp> for the current node. This should be the	220
		221	Example: become a distributed node using the locla node name as profile.
208	most common form of invocation for "daemon"-type nodes.	222	This should be the most common form of invocation for "daemon"-type nodes.
209		223
210	initialise_node;	224	configure
211		225
212	Example: become an anonymous node. This form is often used for commandline	226	Example: become an anonymous node. This form is often used for commandline
213	clients.	227	clients.
214		228
215	initialise_node "anon/";	229	configure nodeid => "anon/";
216		230
217	Example: become a distributed node. If there is no profile of the given	231	Example: configure a node using a profile called seed, which si suitable
218	name, or no binds list was specified, resolve C<localhost:4044> and bind	232	for a seed node as it binds on all local addresses on a fixed port (4040,
219	on the resulting addresses.	233	customary for aemp).
220		234
221	initialise_node "localhost:4044";	235	# use the aemp commandline utility
		236	# aemp profile seed nodeid anon/ binds '*:4040'
		237
		238	# then use it
		239	configure profile => "seed";
		240
		241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
		243
		244	# or provide a nicer-to-remember nodeid
		245	# aemp run profile seed nodeid "$(hostname)"
222		246
223	=item $SELF	247	=item $SELF
224		248
225	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
226	blocks.	250	blocks.
…		…
348		372
349	=cut	373	=cut
350		374
351	sub rcv($@) {	375	sub rcv($@) {
352	my $port = shift;	376	my $port = shift;
353	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($nodeid, $portid) = split /#/, $port, 2;
354		378
355	$NODE{$noderef} == $NODE{""}	379	$NODE{$nodeid} == $NODE{""}
356	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
357		381
358	while (@_) {	382	while (@_) {
359	if (ref $_[0]) {	383	if (ref $_[0]) {
360	if (my $self = $PORT_DATA{$portid}) {	384	if (my $self = $PORT_DATA{$portid}) {
…		…
451		475
452	Monitor the given port and do something when the port is killed or	476	Monitor the given port and do something when the port is killed or
453	messages to it were lost, and optionally return a guard that can be used	477	messages to it were lost, and optionally return a guard that can be used
454	to stop monitoring again.	478	to stop monitoring again.
455		479
		480	In the first form (callback), the callback is simply called with any
		481	number of C<@reason> elements (no @reason means that the port was deleted
		482	"normally"). Note also that I<< the callback B<must> never die >>, so use
		483	C<eval> if unsure.
		484
		485	In the second form (another port given), the other port (C<$rcvport>)
		486	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		487	"normal" kils nothing happens, while under all other conditions, the other
		488	port is killed with the same reason.
		489
		490	The third form (kill self) is the same as the second form, except that
		491	C<$rvport> defaults to C<$SELF>.
		492
		493	In the last form (message), a message of the form C<@msg, @reason> will be
		494	C<snd>.
		495
		496	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		497	alert was raised), they are removed and will not trigger again.
		498
		499	As a rule of thumb, monitoring requests should always monitor a port from
		500	a local port (or callback). The reason is that kill messages might get
		501	lost, just like any other message. Another less obvious reason is that
		502	even monitoring requests can get lost (for example, when the connection
		503	to the other node goes down permanently). When monitoring a port locally
		504	these problems do not exist.
		505
456	C<mon> effectively guarantees that, in the absence of hardware failures,	506	C<mon> effectively guarantees that, in the absence of hardware failures,
457	after starting the monitor, either all messages sent to the port will	507	after starting the monitor, either all messages sent to the port will
458	arrive, or the monitoring action will be invoked after possible message	508	arrive, or the monitoring action will be invoked after possible message
459	loss has been detected. No messages will be lost "in between" (after	509	loss has been detected. No messages will be lost "in between" (after
460	the first lost message no further messages will be received by the	510	the first lost message no further messages will be received by the
461	port). After the monitoring action was invoked, further messages might get	511	port). After the monitoring action was invoked, further messages might get
462	delivered again.	512	delivered again.
463		513
464	Note that monitoring-actions are one-shot: once messages are lost (and a	514	Inter-host-connection timeouts and monitoring depend on the transport
465	monitoring alert was raised), they are removed and will not trigger again.	515	used. The only transport currently implemented is TCP, and AnyEvent::MP
		516	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		517	non-idle connection, and usually around two hours for idle conenctions).
466		518
467	In the first form (callback), the callback is simply called with any	519	This means that monitoring is good for program errors and cleaning up
468	number of C<@reason> elements (no @reason means that the port was deleted	520	stuff eventually, but they are no replacement for a timeout when you need
469	"normally"). Note also that I<< the callback B<must> never die >>, so use	521	to ensure some maximum latency.
470	C<eval> if unsure.
471
472	In the second form (another port given), the other port (C<$rcvport>)
473	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
474	"normal" kils nothing happens, while under all other conditions, the other
475	port is killed with the same reason.
476
477	The third form (kill self) is the same as the second form, except that
478	C<$rvport> defaults to C<$SELF>.
479
480	In the last form (message), a message of the form C<@msg, @reason> will be
481	C<snd>.
482
483	As a rule of thumb, monitoring requests should always monitor a port from
484	a local port (or callback). The reason is that kill messages might get
485	lost, just like any other message. Another less obvious reason is that
486	even monitoring requests can get lost (for exmaple, when the connection
487	to the other node goes down permanently). When monitoring a port locally
488	these problems do not exist.
489		522
490	Example: call a given callback when C<$port> is killed.	523	Example: call a given callback when C<$port> is killed.
491		524
492	mon $port, sub { warn "port died because of <@_>\n" };	525	mon $port, sub { warn "port died because of <@_>\n" };
493		526
…		…
500	mon $port, $self => "restart";	533	mon $port, $self => "restart";
501		534
502	=cut	535	=cut
503		536
504	sub mon {	537	sub mon {
505	my ($noderef, $port) = split /#/, shift, 2;	538	my ($nodeid, $port) = split /#/, shift, 2;
506		539
507	my $node = $NODE{$noderef} \|\| add_node $noderef;	540	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
508		541
509	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	542	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
510		543
511	unless (ref $cb) {	544	unless (ref $cb) {
512	if (@_) {	545	if (@_) {
…		…
626	};	659	};
627	_self_die if $@;	660	_self_die if $@;
628	}	661	}
629		662
630	sub spawn(@) {	663	sub spawn(@) {
631	my ($noderef, undef) = split /#/, shift, 2;	664	my ($nodeid, undef) = split /#/, shift, 2;
632		665
633	my $id = "$RUNIQ." . $ID++;	666	my $id = "$RUNIQ." . $ID++;
634		667
635	$_[0] =~ /::/	668	$_[0] =~ /::/
636	or Carp::croak "spawn init function must be a fully-qualified name, caught";	669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
637		670
638	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;	671	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
639		672
640	"$noderef#$id"	673	"$nodeid#$id"
641	}	674	}
642		675
643	=item after $timeout, @msg	676	=item after $timeout, @msg
644		677
645	=item after $timeout, $callback	678	=item after $timeout, $callback
…		…
684		717
685	=item * Node IDs are arbitrary strings in AEMP.	718	=item * Node IDs are arbitrary strings in AEMP.
686		719
687	Erlang relies on special naming and DNS to work everywhere in the same	720	Erlang relies on special naming and DNS to work everywhere in the same
688	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	721	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
689	configuraiton or DNS), but will otherwise discover other odes itself.	722	configuration or DNS), but will otherwise discover other odes itself.
690		723
691	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	724	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
692	uses "local ports are like remote ports".	725	uses "local ports are like remote ports".
693		726
694	The failure modes for local ports are quite different (runtime errors	727	The failure modes for local ports are quite different (runtime errors
…		…
707		740
708	Erlang uses processes that selectively receive messages, and therefore	741	Erlang uses processes that selectively receive messages, and therefore
709	needs a queue. AEMP is event based, queuing messages would serve no	742	needs a queue. AEMP is event based, queuing messages would serve no
710	useful purpose. For the same reason the pattern-matching abilities of	743	useful purpose. For the same reason the pattern-matching abilities of
711	AnyEvent::MP are more limited, as there is little need to be able to	744	AnyEvent::MP are more limited, as there is little need to be able to
712	filter messages without dequeing them.	745	filter messages without dequeuing them.
713		746
714	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	747	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
715		748
716	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
717		750

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs. Revision 1.79 by root, Fri Sep 4 21:52:09 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC vs.
Revision 1.79 by root, Fri Sep 4 21:52:09 2009 UTC