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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.106 by root, Wed Dec 9 14:00:49 2009 UTC vs.
Revision 1.119 by root, Sun Feb 26 10:29:59 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<#>) as
86	separator, and a port name (a printable string of unspecified format).	88	separator, and a port name (a printable string of unspecified format).
87		89
…		…
91	which enables nodes to manage each other remotely, and to create new	93	which enables nodes to manage each other remotely, and to create new
92	ports.	94	ports.
93		95
94	Nodes are either public (have one or more listening ports) or private	96	Nodes are either public (have one or more listening ports) or private
95	(no listening ports). Private nodes cannot talk to other private nodes	97	(no listening ports). Private nodes cannot talk to other private nodes
96	currently.	98	currently, but all nodes can talk to public nodes.
97		99
		100	Nodes is represented by (printable) strings called "node IDs".
		101
98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>	102	=item node ID - C<[A-Za-z0-9_\-.:]*>
99		103
100	A node ID is a string that uniquely identifies the node within a	104	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	105	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	106	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
103	doesn't interpret node IDs in any way.	107	doesn't interpret node IDs in any way except to uniquely identify a node.
104		108
105	=item binds - C<ip:port>	109	=item binds - C<ip:port>
106		110
107	Nodes can only talk to each other by creating some kind of connection to	111	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	112	each other. To do this, nodes should listen on one or more local transport
		113	endpoints - binds.
		114
109	endpoints - binds. Currently, only standard C<ip:port> specifications can	115	Currently, only standard C<ip:port> specifications can be used, which
110	be used, which specify TCP ports to listen on.	116	specify TCP ports to listen on. So a bind is basically just a tcp socket
		117	in listening mode thta accepts conenctions form other nodes.
111		118
112	=item seed nodes	119	=item seed nodes
113		120
114	When a node starts, it knows nothing about the network. To teach the node	121	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	122	needs to connect to at least one other node that is already in the
116	network. This node is called a seed.	123	network. These other nodes are called "seed nodes".
117		124
118	Apart from the fact that other nodes know them as seed nodes and they have	125	Seed nodes themselves are not special - they are seed nodes only because
119	to have fixed listening addresses, seed nodes are perfectly normal nodes -	126	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.	127	node for other nodes, and eahc node cna use a different set of seed nodes.
121		128
122	In addition to discovering the network, seed nodes are also used to	129	In addition to discovering the network, seed nodes are also used to
123	maintain the network and to connect nodes that otherwise would have	130	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.	131	the same network. If a network is split into multiple subnets because e.g.
		132	the network link between the parts goes down, then using the same seed
		133	nodes for all nodes ensures that eventually the subnets get merged again.
125		134
126	Seed nodes are expected to be long-running, and at least one seed node	135	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	136	should always be available. They should also be relatively responsive - a
128	seed node that blocks for long periods will slow down everybody else.	137	seed node that blocks for long periods will slow down everybody else.
129		138
		139	For small networks, it's best if every node uses the same set of seed
		140	nodes. For large networks, it can be useful to specify "regional" seed
		141	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		142	each other. What's important is that all seed nodes connections form a
		143	complete graph, so that the network cannot split into separate subnets
		144	forever.
		145
		146	Seed nodes are represented by seed IDs.
		147
130	=item seeds - C<host:port>	148	=item seed IDs - C<host:port>
131		149
132	Seeds are transport endpoint(s) (usually a hostname/IP address and a	150	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.	151	TCP port) of nodes that should be used as seed nodes.
134		152
135	The nodes listening on those endpoints are expected to be long-running,	153	=item global nodes
136	and at least one of those should always be available. When nodes run out	154
137	of connections (e.g. due to a network error), they try to re-establish	155	An AEMP network needs a discovery service - nodes need to know how to
138	connections to some seednodes again to join the network.	156	connect to other nodes they only know by name. In addition, AEMP offers a
		157	distributed "group database", which maps group names to a list of strings
		158	- for example, to register worker ports.
		159
		160	A network needs at least one global node to work, and allows every node to
		161	be a global node.
		162
		163	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		164	node and tries to keep connections to all other nodes. So while it can
		165	make sense to make every node "global" in small networks, it usually makes
		166	sense to only make seed nodes into global nodes in large networks (nodes
		167	keep connections to seed nodes and global nodes, so makign them the same
		168	reduces overhead).
139		169
140	=back	170	=back
141		171
142	=head1 VARIABLES/FUNCTIONS	172	=head1 VARIABLES/FUNCTIONS
143		173
…		…
155		185
156	use AE ();	186	use AE ();
157		187
158	use base "Exporter";	188	use base "Exporter";
159		189
160	our $VERSION = 1.24;	190	our $VERSION = '1.30';
161		191
162	our @EXPORT = qw(	192	our @EXPORT = qw(
163	NODE $NODE *SELF node_of after	193	NODE $NODE *SELF node_of after
164	configure	194	configure
165	snd rcv mon mon_guard kil psub peval spawn cal	195	snd rcv mon mon_guard kil psub peval spawn cal
…		…
191	Before a node can talk to other nodes on the network (i.e. enter	221	Before a node can talk to other nodes on the network (i.e. enter
192	"distributed mode") it has to configure itself - the minimum a node needs	222	"distributed mode") it has to configure itself - the minimum a node needs
193	to know is its own name, and optionally it should know the addresses of	223	to know is its own name, and optionally it should know the addresses of
194	some other nodes in the network to discover other nodes.	224	some other nodes in the network to discover other nodes.
195		225
		226	The key/value pairs are basically the same ones as documented for the
		227	F<aemp> command line utility (sans the set/del prefix).
		228
196	This function configures a node - it must be called exactly once (or	229	This function configures a node - it must be called exactly once (or
197	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
198		231
199	=over 4	232	=over 4
200		233
…		…
233	used, meaning the node will bind on a dynamically-assigned port on every	266	used, meaning the node will bind on a dynamically-assigned port on every
234	local IP address it finds.	267	local IP address it finds.
235		268
236	=item step 3, connect to seed nodes	269	=item step 3, connect to seed nodes
237		270
238	As the last step, the seeds list from the profile is passed to the	271	As the last step, the seed ID list from the profile is passed to the
239	L<AnyEvent::MP::Global> module, which will then use it to keep	272	L<AnyEvent::MP::Global> module, which will then use it to keep
240	connectivity with at least one node at any point in time.	273	connectivity with at least one node at any point in time.
241		274
242	=back	275	=back
243		276
…		…
492	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	525	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
493	closure is executed, sets up the environment in the same way as in C<rcv>	526	closure is executed, sets up the environment in the same way as in C<rcv>
494	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	527	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
495		528
496	The effect is basically as if it returned C<< sub { peval $SELF, sub {	529	The effect is basically as if it returned C<< sub { peval $SELF, sub {
497	BLOCK } } >>.	530	BLOCK }, @_ } >>.
498		531
499	This is useful when you register callbacks from C<rcv> callbacks:	532	This is useful when you register callbacks from C<rcv> callbacks:
500		533
501	rcv delayed_reply => sub {	534	rcv delayed_reply => sub {
502	my ($delay, @reply) = @_;	535	my ($delay, @reply) = @_;
…		…
650		683
651	=item kil $port[, @reason]	684	=item kil $port[, @reason]
652		685
653	Kill the specified port with the given C<@reason>.	686	Kill the specified port with the given C<@reason>.
654		687
655	If no C<@reason> is specified, then the port is killed "normally" (ports	688	If no C<@reason> is specified, then the port is killed "normally" -
656	monitoring other ports will not necessarily die because a port dies	689	monitor callback will be invoked, but the kil will not cause linked ports
657	"normally").	690	(C<mon $mport, $lport> form) to get killed.
658		691
659	Otherwise, linked ports get killed with the same reason (second form of	692	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
660	C<mon>, see above).	693	form) get killed with the same reason.
661		694
662	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	695	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
663	will be reported as reason C<< die => $@ >>.	696	will be reported as reason C<< die => $@ >>.
664		697
665	Transport/communication errors are reported as C<< transport_error =>	698	Transport/communication errors are reported as C<< transport_error =>
…		…
859	ports being the special case/exception, where transport errors cannot	892	ports being the special case/exception, where transport errors cannot
860	occur.	893	occur.
861		894
862	=item * Erlang uses processes and a mailbox, AEMP does not queue.	895	=item * Erlang uses processes and a mailbox, AEMP does not queue.
863		896
864	Erlang uses processes that selectively receive messages, and therefore	897	Erlang uses processes that selectively receive messages out of order, and
865	needs a queue. AEMP is event based, queuing messages would serve no	898	therefore needs a queue. AEMP is event based, queuing messages would serve
866	useful purpose. For the same reason the pattern-matching abilities of	899	no useful purpose. For the same reason the pattern-matching abilities
867	AnyEvent::MP are more limited, as there is little need to be able to	900	of AnyEvent::MP are more limited, as there is little need to be able to
868	filter messages without dequeuing them.	901	filter messages without dequeuing them.
869		902
870	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	903	This is not a philosophical difference, but simply stems from AnyEvent::MP
		904	being event-based, while Erlang is process-based.
		905
		906	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		907	top of AEMP and Coro threads.
871		908
872	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
873		910
874	Sending messages in Erlang is synchronous and blocks the process (and	911	Sending messages in Erlang is synchronous and blocks the process until
		912	a conenction has been established and the message sent (and so does not
875	so does not need a queue that can overflow). AEMP sends are immediate,	913	need a queue that can overflow). AEMP sends return immediately, connection
876	connection establishment is handled in the background.	914	establishment is handled in the background.
877		915
878	=item * Erlang suffers from silent message loss, AEMP does not.	916	=item * Erlang suffers from silent message loss, AEMP does not.
879		917
880	Erlang implements few guarantees on messages delivery - messages can get	918	Erlang implements few guarantees on messages delivery - messages can get
881	lost without any of the processes realising it (i.e. you send messages a,	919	lost without any of the processes realising it (i.e. you send messages a,
882	b, and c, and the other side only receives messages a and c).	920	b, and c, and the other side only receives messages a and c).
883		921
884	AEMP guarantees correct ordering, and the guarantee that after one message	922	AEMP guarantees (modulo hardware errors) correct ordering, and the
885	is lost, all following ones sent to the same port are lost as well, until	923	guarantee that after one message is lost, all following ones sent to the
886	monitoring raises an error, so there are no silent "holes" in the message	924	same port are lost as well, until monitoring raises an error, so there are
887	sequence.	925	no silent "holes" in the message sequence.
		926
		927	If you want your software to be very reliable, you have to cope with
		928	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		929	simply tries to work better in common error cases, such as when a network
		930	link goes down.
888		931
889	=item * Erlang can send messages to the wrong port, AEMP does not.	932	=item * Erlang can send messages to the wrong port, AEMP does not.
890		933
891	In Erlang it is quite likely that a node that restarts reuses a process ID	934	In Erlang it is quite likely that a node that restarts reuses an Erlang
892	known to other nodes for a completely different process, causing messages	935	process ID known to other nodes for a completely different process,
893	destined for that process to end up in an unrelated process.	936	causing messages destined for that process to end up in an unrelated
		937	process.
894		938
895	AEMP never reuses port IDs, so old messages or old port IDs floating	939	AEMP does not reuse port IDs, so old messages or old port IDs floating
896	around in the network will not be sent to an unrelated port.	940	around in the network will not be sent to an unrelated port.
897		941
898	=item * Erlang uses unprotected connections, AEMP uses secure	942	=item * Erlang uses unprotected connections, AEMP uses secure
899	authentication and can use TLS.	943	authentication and can use TLS.
900		944
…		…
903		947
904	=item * The AEMP protocol is optimised for both text-based and binary	948	=item * The AEMP protocol is optimised for both text-based and binary
905	communications.	949	communications.
906		950
907	The AEMP protocol, unlike the Erlang protocol, supports both programming	951	The AEMP protocol, unlike the Erlang protocol, supports both programming
908	language independent text-only protocols (good for debugging) and binary,	952	language independent text-only protocols (good for debugging), and binary,
909	language-specific serialisers (e.g. Storable). By default, unless TLS is	953	language-specific serialisers (e.g. Storable). By default, unless TLS is
910	used, the protocol is actually completely text-based.	954	used, the protocol is actually completely text-based.
911		955
912	It has also been carefully designed to be implementable in other languages	956	It has also been carefully designed to be implementable in other languages
913	with a minimum of work while gracefully degrading functionality to make the	957	with a minimum of work while gracefully degrading functionality to make the
914	protocol simple.	958	protocol simple.
915		959
916	=item * AEMP has more flexible monitoring options than Erlang.	960	=item * AEMP has more flexible monitoring options than Erlang.
917		961
918	In Erlang, you can chose to receive I<all> exit signals as messages	962	In Erlang, you can chose to receive I<all> exit signals as messages or
919	or I<none>, there is no in-between, so monitoring single processes is	963	I<none>, there is no in-between, so monitoring single Erlang processes is
920	difficult to implement. Monitoring in AEMP is more flexible than in	964	difficult to implement.
921	Erlang, as one can choose between automatic kill, exit message or callback	965
922	on a per-process basis.	966	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		967	between automatic kill, exit message or callback on a per-port basis.
923		968
924	=item * Erlang tries to hide remote/local connections, AEMP does not.	969	=item * Erlang tries to hide remote/local connections, AEMP does not.
925		970
926	Monitoring in Erlang is not an indicator of process death/crashes, in the	971	Monitoring in Erlang is not an indicator of process death/crashes, in the
927	same way as linking is (except linking is unreliable in Erlang).	972	same way as linking is (except linking is unreliable in Erlang).
…		…
949	overhead, as well as having to keep a proxy object everywhere.	994	overhead, as well as having to keep a proxy object everywhere.
950		995
951	Strings can easily be printed, easily serialised etc. and need no special	996	Strings can easily be printed, easily serialised etc. and need no special
952	procedures to be "valid".	997	procedures to be "valid".
953		998
954	And as a result, a miniport consists of a single closure stored in a	999	And as a result, a port with just a default receiver consists of a single
955	global hash - it can't become much cheaper.	1000	code reference stored in a global hash - it can't become much cheaper.
956		1001
957	=item Why favour JSON, why not a real serialising format such as Storable?	1002	=item Why favour JSON, why not a real serialising format such as Storable?
958		1003
959	In fact, any AnyEvent::MP node will happily accept Storable as framing	1004	In fact, any AnyEvent::MP node will happily accept Storable as framing
960	format, but currently there is no way to make a node use Storable by	1005	format, but currently there is no way to make a node use Storable by
…		…
976		1021
977	L<AnyEvent::MP::Intro> - a gentle introduction.	1022	L<AnyEvent::MP::Intro> - a gentle introduction.
978		1023
979	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
980		1025
981	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1026	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
982	your applications.	1027	your applications.
983		1028
984	L<AnyEvent::MP::DataConn> - establish data connections between nodes.	1029	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
985		1030
986	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1031	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.106 by root, Wed Dec 9 14:00:49 2009 UTC vs. Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.106 by root, Wed Dec 9 14:00:49 2009 UTC vs.
Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC