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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.114 by root, Thu Apr 22 16:06:19 2010 UTC vs.
Revision 1.125 by root, Sat Mar 3 13:07:19 2012 UTC

…		…
30	rcv $port, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
31		31
32	# create a port on another node	32	# create a port on another node
33	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
34		34
35	# destroy a prot again	35	# destroy a port again
36	kil $port; # "normal" kill	36	kil $port; # "normal" kill
37	kil $port, my_error => "everything is broken"; # error kill	37	kil $port, my_error => "everything is broken"; # error kill
38		38
39	# monitoring	39	# monitoring
40	mon $localport, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
…		…
78		78
79	Ports allow you to register C<rcv> handlers that can match all or just	79	Ports allow you to register C<rcv> handlers that can match all or just
80	some messages. Messages send to ports will not be queued, regardless of	80	some messages. Messages send to ports will not be queued, regardless of
81	anything was listening for them or not.	81	anything was listening for them or not.
82		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
83	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
84		86
85	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>)
86	separator, and a port name (a printable string of unspecified format).	88	as separator, and a port name (a printable string of unspecified
		89	format created by AnyEvent::MP).
87		90
88	=item node	91	=item node
89		92
90	A node is a single process containing at least one port - the node port,	93	A node is a single process containing at least one port - the node port,
91	which enables nodes to manage each other remotely, and to create new	94	which enables nodes to manage each other remotely, and to create new
92	ports.	95	ports.
93		96
94	Nodes are either public (have one or more listening ports) or private	97	Nodes are either public (have one or more listening ports) or private
95	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
96	currently.	99	currently, but all nodes can talk to public nodes.
97		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
99		104
100	A node ID is a string that uniquely identifies the node within a	105	A node ID is a string that uniquely identifies the node within a
101	network. Depending on the configuration used, node IDs can look like a	106	network. Depending on the configuration used, node IDs can look like a
102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	107	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
103	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
104		109
105	=item binds - C<ip:port>	110	=item binds - C<ip:port>
106		111
107	Nodes can only talk to each other by creating some kind of connection to	112	Nodes can only talk to each other by creating some kind of connection to
108	each other. To do this, nodes should listen on one or more local transport	113	each other. To do this, nodes should listen on one or more local transport
		114	endpoints - binds.
		115
109	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
110	be used, which specify TCP ports to listen on.	117	specify TCP ports to listen on. So a bind is basically just a tcp socket
		118	in listening mode thta accepts conenctions form other nodes.
111		119
112	=item seed nodes	120	=item seed nodes
113		121
114	When a node starts, it knows nothing about the network. To teach the node	122	When a node starts, it knows nothing about the network it is in - it
115	about the network it first has to contact some other node within the	123	needs to connect to at least one other node that is already in the
116	network. This node is called a seed.	124	network. These other nodes are called "seed nodes".
117		125
118	Apart from the fact that other nodes know them as seed nodes and they have	126	Seed nodes themselves are not special - they are seed nodes only because
119	to have fixed listening addresses, seed nodes are perfectly normal nodes -	127	some other node I<uses> them as such, but any node can be used as seed
120	any node can function as a seed node for others.	128	node for other nodes, and eahc node cna use a different set of seed nodes.
121		129
122	In addition to discovering the network, seed nodes are also used to	130	In addition to discovering the network, seed nodes are also used to
123	maintain the network and to connect nodes that otherwise would have	131	maintain the network - all nodes using the same seed node form are part of
124	trouble connecting. They form the backbone of an AnyEvent::MP network.	132	the same network. If a network is split into multiple subnets because e.g.
		133	the network link between the parts goes down, then using the same seed
		134	nodes for all nodes ensures that eventually the subnets get merged again.
125		135
126	Seed nodes are expected to be long-running, and at least one seed node	136	Seed nodes are expected to be long-running, and at least one seed node
127	should always be available. They should also be relatively responsive - a	137	should always be available. They should also be relatively responsive - a
128	seed node that blocks for long periods will slow down everybody else.	138	seed node that blocks for long periods will slow down everybody else.
129		139
		140	For small networks, it's best if every node uses the same set of seed
		141	nodes. For large networks, it can be useful to specify "regional" seed
		142	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		143	each other. What's important is that all seed nodes connections form a
		144	complete graph, so that the network cannot split into separate subnets
		145	forever.
		146
		147	Seed nodes are represented by seed IDs.
		148
130	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
131		150
132	Seeds are transport endpoint(s) (usually a hostname/IP address and a	151	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
133	TCP port) of nodes that should be used as seed nodes.	152	TCP port) of nodes that should be used as seed nodes.
134		153
135	The nodes listening on those endpoints are expected to be long-running,	154	=item global nodes
136	and at least one of those should always be available. When nodes run out	155
137	of connections (e.g. due to a network error), they try to re-establish	156	An AEMP network needs a discovery service - nodes need to know how to
138	connections to some seednodes again to join the network.	157	connect to other nodes they only know by name. In addition, AEMP offers a
		158	distributed "group database", which maps group names to a list of strings
		159	- for example, to register worker ports.
		160
		161	A network needs at least one global node to work, and allows every node to
		162	be a global node.
		163
		164	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		165	node and tries to keep connections to all other nodes. So while it can
		166	make sense to make every node "global" in small networks, it usually makes
		167	sense to only make seed nodes into global nodes in large networks (nodes
		168	keep connections to seed nodes and global nodes, so makign them the same
		169	reduces overhead).
139		170
140	=back	171	=back
141		172
142	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
143		174
…		…
145		176
146	=cut	177	=cut
147		178
148	package AnyEvent::MP;	179	package AnyEvent::MP;
149		180
		181	use AnyEvent::MP::Config ();
150	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
151		184
152	use common::sense;	185	use common::sense;
153		186
154	use Carp ();	187	use Carp ();
155		188
156	use AE ();	189	use AE ();
		190	use Guard ();
157		191
158	use base "Exporter";	192	use base "Exporter";
159		193
160	our $VERSION = 1.28;	194	our $VERSION = $AnyEvent::MP::Config::VERSION;
161		195
162	our @EXPORT = qw(	196	our @EXPORT = qw(
163	NODE $NODE *SELF node_of after	197	NODE $NODE *SELF node_of after
164	configure	198	configure
165	snd rcv mon mon_guard kil psub peval spawn cal	199	snd rcv mon mon_guard kil psub peval spawn cal
166	port	200	port
		201	db_set db_del db_reg
167	);	202	);
168		203
169	our $SELF;	204	our $SELF;
170		205
171	sub _self_die() {	206	sub _self_die() {
…		…
191	Before a node can talk to other nodes on the network (i.e. enter	226	Before a node can talk to other nodes on the network (i.e. enter
192	"distributed mode") it has to configure itself - the minimum a node needs	227	"distributed mode") it has to configure itself - the minimum a node needs
193	to know is its own name, and optionally it should know the addresses of	228	to know is its own name, and optionally it should know the addresses of
194	some other nodes in the network to discover other nodes.	229	some other nodes in the network to discover other nodes.
195		230
196	The key/value pairs are basically the same ones as documented for the
197	F<aemp> command line utility (sans the set/del prefix).
198
199	This function configures a node - it must be called exactly once (or	231	This function configures a node - it must be called exactly once (or
200	never) before calling other AnyEvent::MP functions.	232	never) before calling other AnyEvent::MP functions.
		233
		234	The key/value pairs are basically the same ones as documented for the
		235	F<aemp> command line utility (sans the set/del prefix), with two additions:
		236
		237	=over 4
		238
		239	=item norc => $boolean (default false)
		240
		241	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		242	be consulted - all configuraiton options must be specified in the
		243	C<configure> call.
		244
		245	=item force => $boolean (default false)
		246
		247	IF true, then the values specified in the C<configure> will take
		248	precedence over any values configured via the rc file. The default is for
		249	the rc file to override any options specified in the program.
		250
		251	=back
201		252
202	=over 4	253	=over 4
203		254
204	=item step 1, gathering configuration from profiles	255	=item step 1, gathering configuration from profiles
205		256
…		…
219	That means that the values specified in the profile have highest priority	270	That means that the values specified in the profile have highest priority
220	and the values specified directly via C<configure> have lowest priority,	271	and the values specified directly via C<configure> have lowest priority,
221	and can only be used to specify defaults.	272	and can only be used to specify defaults.
222		273
223	If the profile specifies a node ID, then this will become the node ID of	274	If the profile specifies a node ID, then this will become the node ID of
224	this process. If not, then the profile name will be used as node ID. The	275	this process. If not, then the profile name will be used as node ID, with
225	special node ID of C<anon/> will be replaced by a random node ID.	276	a slash (C</>) attached.
		277
		278	If the node ID (or profile name) ends with a slash (C</>), then a random
		279	string is appended to make it unique.
226		280
227	=item step 2, bind listener sockets	281	=item step 2, bind listener sockets
228		282
229	The next step is to look up the binds in the profile, followed by binding	283	The next step is to look up the binds in the profile, followed by binding
230	aemp protocol listeners on all binds specified (it is possible and valid	284	aemp protocol listeners on all binds specified (it is possible and valid
…		…
236	used, meaning the node will bind on a dynamically-assigned port on every	290	used, meaning the node will bind on a dynamically-assigned port on every
237	local IP address it finds.	291	local IP address it finds.
238		292
239	=item step 3, connect to seed nodes	293	=item step 3, connect to seed nodes
240		294
241	As the last step, the seeds list from the profile is passed to the	295	As the last step, the seed ID list from the profile is passed to the
242	L<AnyEvent::MP::Global> module, which will then use it to keep	296	L<AnyEvent::MP::Global> module, which will then use it to keep
243	connectivity with at least one node at any point in time.	297	connectivity with at least one node at any point in time.
244		298
245	=back	299	=back
246		300
…		…
252	Example: become an anonymous node. This form is often used for commandline	306	Example: become an anonymous node. This form is often used for commandline
253	clients.	307	clients.
254		308
255	configure nodeid => "anon/";	309	configure nodeid => "anon/";
256		310
257	Example: configure a node using a profile called seed, which si suitable	311	Example: configure a node using a profile called seed, which is suitable
258	for a seed node as it binds on all local addresses on a fixed port (4040,	312	for a seed node as it binds on all local addresses on a fixed port (4040,
259	customary for aemp).	313	customary for aemp).
260		314
261	# use the aemp commandline utility	315	# use the aemp commandline utility
262	# aemp profile seed nodeid anon/ binds '*:4040'	316	# aemp profile seed binds '*:4040'
263		317
264	# then use it	318	# then use it
265	configure profile => "seed";	319	configure profile => "seed";
266		320
267	# or simply use aemp from the shell again:	321	# or simply use aemp from the shell again:
…		…
337	sub _kilme {	391	sub _kilme {
338	die "received message on port without callback";	392	die "received message on port without callback";
339	}	393	}
340		394
341	sub port(;&) {	395	sub port(;&) {
342	my $id = "$UNIQ." . $ID++;	396	my $id = $UNIQ . ++$ID;
343	my $port = "$NODE#$id";	397	my $port = "$NODE#$id";
344		398
345	rcv $port, shift \|\| \&_kilme;	399	rcv $port, shift \|\| \&_kilme;
346		400
347	$port	401	$port
…		…
620	}	674	}
621		675
622	$node->monitor ($port, $cb);	676	$node->monitor ($port, $cb);
623		677
624	defined wantarray	678	defined wantarray
625	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })	679	and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) })
626	}	680	}
627		681
628	=item $guard = mon_guard $port, $ref, $ref...	682	=item $guard = mon_guard $port, $ref, $ref...
629		683
630	Monitors the given C<$port> and keeps the passed references. When the port	684	Monitors the given C<$port> and keeps the passed references. When the port
…		…
734	}	788	}
735		789
736	sub spawn(@) {	790	sub spawn(@) {
737	my ($nodeid, undef) = split /#/, shift, 2;	791	my ($nodeid, undef) = split /#/, shift, 2;
738		792
739	my $id = "$RUNIQ." . $ID++;	793	my $id = $RUNIQ . ++$ID;
740		794
741	$_[0] =~ /::/	795	$_[0] =~ /::/
742	or Carp::croak "spawn init function must be a fully-qualified name, caught";	796	or Carp::croak "spawn init function must be a fully-qualified name, caught";
743		797
744	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	798	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
745		799
746	"$nodeid#$id"	800	"$nodeid#$id"
747	}	801	}
		802
748		803
749	=item after $timeout, @msg	804	=item after $timeout, @msg
750		805
751	=item after $timeout, $callback	806	=item after $timeout, $callback
752		807
…		…
822	$port	877	$port
823	}	878	}
824		879
825	=back	880	=back
826		881
		882	=head1 DISTRIBUTED DATABASE
		883
		884	AnyEvent::MP comes with a simple distributed database. The database will
		885	be mirrored asynchronously at all global nodes. Other nodes bind to one of
		886	the global nodes for their needs.
		887
		888	The database consists of a two-level hash - a hash contains a hash which
		889	contains values.
		890
		891	The top level hash key is called "family", and the second-level hash key
		892	is simply called "key".
		893
		894	The family must be alphanumeric, i.e. start with a letter and consist
		895	of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>,
		896	pretty much like Perl module names.
		897
		898	As the family namespace is global, it is recommended to prefix family names
		899	with the name of the application or module using it.
		900
		901	The keys must be strings, with no other limitations.
		902
		903	The values should preferably be strings, but other perl scalars should
		904	work as well (such as undef, arrays and hashes).
		905
		906	Every database entry is owned by one node - adding the same family/key
		907	combination on multiple nodes will not cause discomfort for AnyEvent::MP,
		908	but the result might be nondeterministic, i.e. the key might have
		909	different values on different nodes.
		910
		911	=item db_set $family => $key => $value
		912
		913	Sets (or replaces) a key to the database.
		914
		915	=item db_del $family => $key
		916
		917	Deletes a key from the database.
		918
		919	=item $guard = db_reg $family => $key [=> $value]
		920
		921	Sets the key on the database and returns a guard. When the guard is
		922	destroyed, the key is deleted from the database. If C<$value> is missing,
		923	then C<undef> is used.
		924
		925	=cut
		926
		927	=back
		928
827	=head1 AnyEvent::MP vs. Distributed Erlang	929	=head1 AnyEvent::MP vs. Distributed Erlang
828		930
829	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	931	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
830	== aemp node, Erlang process == aemp port), so many of the documents and	932	== aemp node, Erlang process == aemp port), so many of the documents and
831	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	933	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
…		…
862	ports being the special case/exception, where transport errors cannot	964	ports being the special case/exception, where transport errors cannot
863	occur.	965	occur.
864		966
865	=item * Erlang uses processes and a mailbox, AEMP does not queue.	967	=item * Erlang uses processes and a mailbox, AEMP does not queue.
866		968
867	Erlang uses processes that selectively receive messages, and therefore	969	Erlang uses processes that selectively receive messages out of order, and
868	needs a queue. AEMP is event based, queuing messages would serve no	970	therefore needs a queue. AEMP is event based, queuing messages would serve
869	useful purpose. For the same reason the pattern-matching abilities of	971	no useful purpose. For the same reason the pattern-matching abilities
870	AnyEvent::MP are more limited, as there is little need to be able to	972	of AnyEvent::MP are more limited, as there is little need to be able to
871	filter messages without dequeuing them.	973	filter messages without dequeuing them.
872		974
873	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	975	This is not a philosophical difference, but simply stems from AnyEvent::MP
		976	being event-based, while Erlang is process-based.
		977
		978	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		979	top of AEMP and Coro threads.
874		980
875	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	981	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
876		982
877	Sending messages in Erlang is synchronous and blocks the process (and	983	Sending messages in Erlang is synchronous and blocks the process until
		984	a conenction has been established and the message sent (and so does not
878	so does not need a queue that can overflow). AEMP sends are immediate,	985	need a queue that can overflow). AEMP sends return immediately, connection
879	connection establishment is handled in the background.	986	establishment is handled in the background.
880		987
881	=item * Erlang suffers from silent message loss, AEMP does not.	988	=item * Erlang suffers from silent message loss, AEMP does not.
882		989
883	Erlang implements few guarantees on messages delivery - messages can get	990	Erlang implements few guarantees on messages delivery - messages can get
884	lost without any of the processes realising it (i.e. you send messages a,	991	lost without any of the processes realising it (i.e. you send messages a,
885	b, and c, and the other side only receives messages a and c).	992	b, and c, and the other side only receives messages a and c).
886		993
887	AEMP guarantees correct ordering, and the guarantee that after one message	994	AEMP guarantees (modulo hardware errors) correct ordering, and the
888	is lost, all following ones sent to the same port are lost as well, until	995	guarantee that after one message is lost, all following ones sent to the
889	monitoring raises an error, so there are no silent "holes" in the message	996	same port are lost as well, until monitoring raises an error, so there are
890	sequence.	997	no silent "holes" in the message sequence.
		998
		999	If you want your software to be very reliable, you have to cope with
		1000	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		1001	simply tries to work better in common error cases, such as when a network
		1002	link goes down.
891		1003
892	=item * Erlang can send messages to the wrong port, AEMP does not.	1004	=item * Erlang can send messages to the wrong port, AEMP does not.
893		1005
894	In Erlang it is quite likely that a node that restarts reuses a process ID	1006	In Erlang it is quite likely that a node that restarts reuses an Erlang
895	known to other nodes for a completely different process, causing messages	1007	process ID known to other nodes for a completely different process,
896	destined for that process to end up in an unrelated process.	1008	causing messages destined for that process to end up in an unrelated
		1009	process.
897		1010
898	AEMP never reuses port IDs, so old messages or old port IDs floating	1011	AEMP does not reuse port IDs, so old messages or old port IDs floating
899	around in the network will not be sent to an unrelated port.	1012	around in the network will not be sent to an unrelated port.
900		1013
901	=item * Erlang uses unprotected connections, AEMP uses secure	1014	=item * Erlang uses unprotected connections, AEMP uses secure
902	authentication and can use TLS.	1015	authentication and can use TLS.
903		1016
…		…
906		1019
907	=item * The AEMP protocol is optimised for both text-based and binary	1020	=item * The AEMP protocol is optimised for both text-based and binary
908	communications.	1021	communications.
909		1022
910	The AEMP protocol, unlike the Erlang protocol, supports both programming	1023	The AEMP protocol, unlike the Erlang protocol, supports both programming
911	language independent text-only protocols (good for debugging) and binary,	1024	language independent text-only protocols (good for debugging), and binary,
912	language-specific serialisers (e.g. Storable). By default, unless TLS is	1025	language-specific serialisers (e.g. Storable). By default, unless TLS is
913	used, the protocol is actually completely text-based.	1026	used, the protocol is actually completely text-based.
914		1027
915	It has also been carefully designed to be implementable in other languages	1028	It has also been carefully designed to be implementable in other languages
916	with a minimum of work while gracefully degrading functionality to make the	1029	with a minimum of work while gracefully degrading functionality to make the
917	protocol simple.	1030	protocol simple.
918		1031
919	=item * AEMP has more flexible monitoring options than Erlang.	1032	=item * AEMP has more flexible monitoring options than Erlang.
920		1033
921	In Erlang, you can chose to receive I<all> exit signals as messages	1034	In Erlang, you can chose to receive I<all> exit signals as messages or
922	or I<none>, there is no in-between, so monitoring single processes is	1035	I<none>, there is no in-between, so monitoring single Erlang processes is
923	difficult to implement. Monitoring in AEMP is more flexible than in	1036	difficult to implement.
924	Erlang, as one can choose between automatic kill, exit message or callback	1037
925	on a per-process basis.	1038	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		1039	between automatic kill, exit message or callback on a per-port basis.
926		1040
927	=item * Erlang tries to hide remote/local connections, AEMP does not.	1041	=item * Erlang tries to hide remote/local connections, AEMP does not.
928		1042
929	Monitoring in Erlang is not an indicator of process death/crashes, in the	1043	Monitoring in Erlang is not an indicator of process death/crashes, in the
930	same way as linking is (except linking is unreliable in Erlang).	1044	same way as linking is (except linking is unreliable in Erlang).
…		…
953		1067
954	Strings can easily be printed, easily serialised etc. and need no special	1068	Strings can easily be printed, easily serialised etc. and need no special
955	procedures to be "valid".	1069	procedures to be "valid".
956		1070
957	And as a result, a port with just a default receiver consists of a single	1071	And as a result, a port with just a default receiver consists of a single
958	closure stored in a global hash - it can't become much cheaper.	1072	code reference stored in a global hash - it can't become much cheaper.
959		1073
960	=item Why favour JSON, why not a real serialising format such as Storable?	1074	=item Why favour JSON, why not a real serialising format such as Storable?
961		1075
962	In fact, any AnyEvent::MP node will happily accept Storable as framing	1076	In fact, any AnyEvent::MP node will happily accept Storable as framing
963	format, but currently there is no way to make a node use Storable by	1077	format, but currently there is no way to make a node use Storable by

Diff Legend

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

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.114 by root, Thu Apr 22 16:06:19 2010 UTC vs. Revision 1.125 by root, Sat Mar 3 13:07:19 2012 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.114 by root, Thu Apr 22 16:06:19 2010 UTC vs.
Revision 1.125 by root, Sat Mar 3 13:07:19 2012 UTC