… | |
… | |
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 port again |
|
|
36 | kil $port; # "normal" kill |
|
|
37 | kil $port, my_error => "everything is broken"; # error kill |
|
|
38 | |
35 | # monitoring |
39 | # monitoring |
36 | mon $localport, $cb->(@msg) # callback is invoked on death |
40 | mon $localport, $cb->(@msg) # callback is invoked on death |
37 | mon $localport, $otherport # kill otherport on abnormal death |
41 | mon $localport, $otherport # kill otherport on abnormal death |
38 | mon $localport, $otherport, @msg # send message on death |
42 | mon $localport, $otherport, @msg # send message on death |
|
|
43 | |
|
|
44 | # temporarily execute code in port context |
|
|
45 | peval $port, sub { die "kill the port!" }; |
|
|
46 | |
|
|
47 | # execute callbacks in $SELF port context |
|
|
48 | my $timer = AE::timer 1, 0, psub { |
|
|
49 | die "kill the port, delayed"; |
|
|
50 | }; |
39 | |
51 | |
40 | =head1 CURRENT STATUS |
52 | =head1 CURRENT STATUS |
41 | |
53 | |
42 | bin/aemp - stable. |
54 | bin/aemp - stable. |
43 | AnyEvent::MP - stable API, should work. |
55 | AnyEvent::MP - stable API, should work. |
… | |
… | |
66 | |
78 | |
67 | 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 |
68 | 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 |
69 | anything was listening for them or not. |
81 | anything was listening for them or not. |
70 | |
82 | |
|
|
83 | Ports are represented by (printable) strings called "port IDs". |
|
|
84 | |
71 | =item port ID - C<nodeid#portname> |
85 | =item port ID - C<nodeid#portname> |
72 | |
86 | |
73 | 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 |
74 | separator, and a port name (a printable string of unspecified format). |
88 | separator, and a port name (a printable string of unspecified format). |
75 | |
89 | |
… | |
… | |
79 | 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 |
80 | ports. |
94 | ports. |
81 | |
95 | |
82 | 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 |
83 | (no listening ports). Private nodes cannot talk to other private nodes |
97 | (no listening ports). Private nodes cannot talk to other private nodes |
84 | currently. |
98 | currently, but all nodes can talk to public nodes. |
85 | |
99 | |
|
|
100 | Nodes is represented by (printable) strings called "node IDs". |
|
|
101 | |
86 | =item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*> |
102 | =item node ID - C<[A-Za-z0-9_\-.:]*> |
87 | |
103 | |
88 | 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 |
89 | 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 |
90 | 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 |
91 | doesn't interpret node IDs in any way. |
107 | doesn't interpret node IDs in any way except to uniquely identify a node. |
92 | |
108 | |
93 | =item binds - C<ip:port> |
109 | =item binds - C<ip:port> |
94 | |
110 | |
95 | 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 |
96 | 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 | |
97 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
115 | Currently, only standard C<ip:port> specifications can be used, which |
98 | 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. |
99 | |
118 | |
100 | =item seed nodes |
119 | =item seed nodes |
101 | |
120 | |
102 | 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 |
103 | 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 |
104 | network. This node is called a seed. |
123 | network. These other nodes are called "seed nodes". |
105 | |
124 | |
106 | 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 |
107 | 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 |
108 | 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. |
109 | |
128 | |
110 | 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 |
111 | 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 |
112 | 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. |
113 | |
134 | |
114 | 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 |
115 | should always be available. They should also be relatively responsive - a |
136 | should always be available. They should also be relatively responsive - a |
116 | 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. |
117 | |
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 | |
118 | =item seeds - C<host:port> |
148 | =item seed IDs - C<host:port> |
119 | |
149 | |
120 | 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 |
121 | TCP port) of nodes that should be used as seed nodes. |
151 | TCP port) of nodes that should be used as seed nodes. |
122 | |
152 | |
123 | The nodes listening on those endpoints are expected to be long-running, |
153 | =item global nodes |
124 | and at least one of those should always be available. When nodes run out |
154 | |
125 | 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 |
126 | 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). |
127 | |
169 | |
128 | =back |
170 | =back |
129 | |
171 | |
130 | =head1 VARIABLES/FUNCTIONS |
172 | =head1 VARIABLES/FUNCTIONS |
131 | |
173 | |
… | |
… | |
133 | |
175 | |
134 | =cut |
176 | =cut |
135 | |
177 | |
136 | package AnyEvent::MP; |
178 | package AnyEvent::MP; |
137 | |
179 | |
|
|
180 | use AnyEvent::MP::Config (); |
138 | use AnyEvent::MP::Kernel; |
181 | use AnyEvent::MP::Kernel; |
|
|
182 | use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID); |
139 | |
183 | |
140 | use common::sense; |
184 | use common::sense; |
141 | |
185 | |
142 | use Carp (); |
186 | use Carp (); |
143 | |
187 | |
144 | use AE (); |
188 | use AE (); |
145 | |
189 | |
146 | use base "Exporter"; |
190 | use base "Exporter"; |
147 | |
191 | |
148 | our $VERSION = 1.21; |
192 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
149 | |
193 | |
150 | our @EXPORT = qw( |
194 | our @EXPORT = qw( |
151 | NODE $NODE *SELF node_of after |
195 | NODE $NODE *SELF node_of after |
152 | configure |
196 | configure |
153 | snd rcv mon mon_guard kil psub spawn cal |
197 | snd rcv mon mon_guard kil psub peval spawn cal |
154 | port |
198 | port |
155 | ); |
199 | ); |
156 | |
200 | |
157 | our $SELF; |
201 | our $SELF; |
158 | |
202 | |
… | |
… | |
181 | to know is its own name, and optionally it should know the addresses of |
225 | to know is its own name, and optionally it should know the addresses of |
182 | some other nodes in the network to discover other nodes. |
226 | some other nodes in the network to discover other nodes. |
183 | |
227 | |
184 | This function configures a node - it must be called exactly once (or |
228 | This function configures a node - it must be called exactly once (or |
185 | never) before calling other AnyEvent::MP functions. |
229 | never) before calling other AnyEvent::MP functions. |
|
|
230 | |
|
|
231 | The key/value pairs are basically the same ones as documented for the |
|
|
232 | F<aemp> command line utility (sans the set/del prefix), with two additions: |
|
|
233 | |
|
|
234 | =over 4 |
|
|
235 | |
|
|
236 | =item norc => $boolean (default false) |
|
|
237 | |
|
|
238 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
|
|
239 | be consulted - all configuraiton options must be specified in the |
|
|
240 | C<configure> call. |
|
|
241 | |
|
|
242 | =item force => $boolean (default false) |
|
|
243 | |
|
|
244 | IF true, then the values specified in the C<configure> will take |
|
|
245 | precedence over any values configured via the rc file. The default is for |
|
|
246 | the rc file to override any options specified in the program. |
|
|
247 | |
|
|
248 | =back |
186 | |
249 | |
187 | =over 4 |
250 | =over 4 |
188 | |
251 | |
189 | =item step 1, gathering configuration from profiles |
252 | =item step 1, gathering configuration from profiles |
190 | |
253 | |
… | |
… | |
204 | That means that the values specified in the profile have highest priority |
267 | That means that the values specified in the profile have highest priority |
205 | and the values specified directly via C<configure> have lowest priority, |
268 | and the values specified directly via C<configure> have lowest priority, |
206 | and can only be used to specify defaults. |
269 | and can only be used to specify defaults. |
207 | |
270 | |
208 | If the profile specifies a node ID, then this will become the node ID of |
271 | If the profile specifies a node ID, then this will become the node ID of |
209 | this process. If not, then the profile name will be used as node ID. The |
272 | this process. If not, then the profile name will be used as node ID, with |
210 | special node ID of C<anon/> will be replaced by a random node ID. |
273 | a slash (C</>) attached. |
|
|
274 | |
|
|
275 | If the node ID (or profile name) ends with a slash (C</>), then a random |
|
|
276 | string is appended to make it unique. |
211 | |
277 | |
212 | =item step 2, bind listener sockets |
278 | =item step 2, bind listener sockets |
213 | |
279 | |
214 | The next step is to look up the binds in the profile, followed by binding |
280 | The next step is to look up the binds in the profile, followed by binding |
215 | aemp protocol listeners on all binds specified (it is possible and valid |
281 | aemp protocol listeners on all binds specified (it is possible and valid |
… | |
… | |
221 | used, meaning the node will bind on a dynamically-assigned port on every |
287 | used, meaning the node will bind on a dynamically-assigned port on every |
222 | local IP address it finds. |
288 | local IP address it finds. |
223 | |
289 | |
224 | =item step 3, connect to seed nodes |
290 | =item step 3, connect to seed nodes |
225 | |
291 | |
226 | As the last step, the seeds list from the profile is passed to the |
292 | As the last step, the seed ID list from the profile is passed to the |
227 | L<AnyEvent::MP::Global> module, which will then use it to keep |
293 | L<AnyEvent::MP::Global> module, which will then use it to keep |
228 | connectivity with at least one node at any point in time. |
294 | connectivity with at least one node at any point in time. |
229 | |
295 | |
230 | =back |
296 | =back |
231 | |
297 | |
… | |
… | |
237 | Example: become an anonymous node. This form is often used for commandline |
303 | Example: become an anonymous node. This form is often used for commandline |
238 | clients. |
304 | clients. |
239 | |
305 | |
240 | configure nodeid => "anon/"; |
306 | configure nodeid => "anon/"; |
241 | |
307 | |
242 | Example: configure a node using a profile called seed, which si suitable |
308 | Example: configure a node using a profile called seed, which is suitable |
243 | for a seed node as it binds on all local addresses on a fixed port (4040, |
309 | for a seed node as it binds on all local addresses on a fixed port (4040, |
244 | customary for aemp). |
310 | customary for aemp). |
245 | |
311 | |
246 | # use the aemp commandline utility |
312 | # use the aemp commandline utility |
247 | # aemp profile seed nodeid anon/ binds '*:4040' |
313 | # aemp profile seed binds '*:4040' |
248 | |
314 | |
249 | # then use it |
315 | # then use it |
250 | configure profile => "seed"; |
316 | configure profile => "seed"; |
251 | |
317 | |
252 | # or simply use aemp from the shell again: |
318 | # or simply use aemp from the shell again: |
… | |
… | |
322 | sub _kilme { |
388 | sub _kilme { |
323 | die "received message on port without callback"; |
389 | die "received message on port without callback"; |
324 | } |
390 | } |
325 | |
391 | |
326 | sub port(;&) { |
392 | sub port(;&) { |
327 | my $id = "$UNIQ." . $ID++; |
393 | my $id = "$UNIQ." . ++$ID; |
328 | my $port = "$NODE#$id"; |
394 | my $port = "$NODE#$id"; |
329 | |
395 | |
330 | rcv $port, shift || \&_kilme; |
396 | rcv $port, shift || \&_kilme; |
331 | |
397 | |
332 | $port |
398 | $port |
… | |
… | |
371 | msg1 => sub { ... }, |
437 | msg1 => sub { ... }, |
372 | ... |
438 | ... |
373 | ; |
439 | ; |
374 | |
440 | |
375 | Example: temporarily register a rcv callback for a tag matching some port |
441 | Example: temporarily register a rcv callback for a tag matching some port |
376 | (e.g. for a rpc reply) and unregister it after a message was received. |
442 | (e.g. for an rpc reply) and unregister it after a message was received. |
377 | |
443 | |
378 | rcv $port, $otherport => sub { |
444 | rcv $port, $otherport => sub { |
379 | my @reply = @_; |
445 | my @reply = @_; |
380 | |
446 | |
381 | rcv $SELF, $otherport; |
447 | rcv $SELF, $otherport; |
… | |
… | |
394 | if (ref $_[0]) { |
460 | if (ref $_[0]) { |
395 | if (my $self = $PORT_DATA{$portid}) { |
461 | if (my $self = $PORT_DATA{$portid}) { |
396 | "AnyEvent::MP::Port" eq ref $self |
462 | "AnyEvent::MP::Port" eq ref $self |
397 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
463 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
398 | |
464 | |
399 | $self->[2] = shift; |
465 | $self->[0] = shift; |
400 | } else { |
466 | } else { |
401 | my $cb = shift; |
467 | my $cb = shift; |
402 | $PORT{$portid} = sub { |
468 | $PORT{$portid} = sub { |
403 | local $SELF = $port; |
469 | local $SELF = $port; |
404 | eval { &$cb }; _self_die if $@; |
470 | eval { &$cb }; _self_die if $@; |
405 | }; |
471 | }; |
406 | } |
472 | } |
407 | } elsif (defined $_[0]) { |
473 | } elsif (defined $_[0]) { |
408 | my $self = $PORT_DATA{$portid} ||= do { |
474 | my $self = $PORT_DATA{$portid} ||= do { |
409 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
475 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
410 | |
476 | |
411 | $PORT{$portid} = sub { |
477 | $PORT{$portid} = sub { |
412 | local $SELF = $port; |
478 | local $SELF = $port; |
413 | |
479 | |
414 | if (my $cb = $self->[1]{$_[0]}) { |
480 | if (my $cb = $self->[1]{$_[0]}) { |
… | |
… | |
436 | } |
502 | } |
437 | |
503 | |
438 | $port |
504 | $port |
439 | } |
505 | } |
440 | |
506 | |
|
|
507 | =item peval $port, $coderef[, @args] |
|
|
508 | |
|
|
509 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
|
|
510 | when the code throews an exception the C<$port> will be killed. |
|
|
511 | |
|
|
512 | Any remaining args will be passed to the callback. Any return values will |
|
|
513 | be returned to the caller. |
|
|
514 | |
|
|
515 | This is useful when you temporarily want to execute code in the context of |
|
|
516 | a port. |
|
|
517 | |
|
|
518 | Example: create a port and run some initialisation code in it's context. |
|
|
519 | |
|
|
520 | my $port = port { ... }; |
|
|
521 | |
|
|
522 | peval $port, sub { |
|
|
523 | init |
|
|
524 | or die "unable to init"; |
|
|
525 | }; |
|
|
526 | |
|
|
527 | =cut |
|
|
528 | |
|
|
529 | sub peval($$) { |
|
|
530 | local $SELF = shift; |
|
|
531 | my $cb = shift; |
|
|
532 | |
|
|
533 | if (wantarray) { |
|
|
534 | my @res = eval { &$cb }; |
|
|
535 | _self_die if $@; |
|
|
536 | @res |
|
|
537 | } else { |
|
|
538 | my $res = eval { &$cb }; |
|
|
539 | _self_die if $@; |
|
|
540 | $res |
|
|
541 | } |
|
|
542 | } |
|
|
543 | |
441 | =item $closure = psub { BLOCK } |
544 | =item $closure = psub { BLOCK } |
442 | |
545 | |
443 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
546 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
444 | closure is executed, sets up the environment in the same way as in C<rcv> |
547 | closure is executed, sets up the environment in the same way as in C<rcv> |
445 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
548 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
549 | |
|
|
550 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
|
|
551 | BLOCK }, @_ } >>. |
446 | |
552 | |
447 | This is useful when you register callbacks from C<rcv> callbacks: |
553 | This is useful when you register callbacks from C<rcv> callbacks: |
448 | |
554 | |
449 | rcv delayed_reply => sub { |
555 | rcv delayed_reply => sub { |
450 | my ($delay, @reply) = @_; |
556 | my ($delay, @reply) = @_; |
… | |
… | |
598 | |
704 | |
599 | =item kil $port[, @reason] |
705 | =item kil $port[, @reason] |
600 | |
706 | |
601 | Kill the specified port with the given C<@reason>. |
707 | Kill the specified port with the given C<@reason>. |
602 | |
708 | |
603 | If no C<@reason> is specified, then the port is killed "normally" (ports |
709 | If no C<@reason> is specified, then the port is killed "normally" - |
604 | monitoring other ports will not necessarily die because a port dies |
710 | monitor callback will be invoked, but the kil will not cause linked ports |
605 | "normally"). |
711 | (C<mon $mport, $lport> form) to get killed. |
606 | |
712 | |
607 | Otherwise, linked ports get killed with the same reason (second form of |
713 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
608 | C<mon>, see above). |
714 | form) get killed with the same reason. |
609 | |
715 | |
610 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
716 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
611 | will be reported as reason C<< die => $@ >>. |
717 | will be reported as reason C<< die => $@ >>. |
612 | |
718 | |
613 | Transport/communication errors are reported as C<< transport_error => |
719 | Transport/communication errors are reported as C<< transport_error => |
… | |
… | |
679 | } |
785 | } |
680 | |
786 | |
681 | sub spawn(@) { |
787 | sub spawn(@) { |
682 | my ($nodeid, undef) = split /#/, shift, 2; |
788 | my ($nodeid, undef) = split /#/, shift, 2; |
683 | |
789 | |
684 | my $id = "$RUNIQ." . $ID++; |
790 | my $id = "$RUNIQ." . ++$ID; |
685 | |
791 | |
686 | $_[0] =~ /::/ |
792 | $_[0] =~ /::/ |
687 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
793 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
688 | |
794 | |
689 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
795 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
690 | |
796 | |
691 | "$nodeid#$id" |
797 | "$nodeid#$id" |
692 | } |
798 | } |
|
|
799 | |
693 | |
800 | |
694 | =item after $timeout, @msg |
801 | =item after $timeout, @msg |
695 | |
802 | |
696 | =item after $timeout, $callback |
803 | =item after $timeout, $callback |
697 | |
804 | |
… | |
… | |
807 | ports being the special case/exception, where transport errors cannot |
914 | ports being the special case/exception, where transport errors cannot |
808 | occur. |
915 | occur. |
809 | |
916 | |
810 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
917 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
811 | |
918 | |
812 | Erlang uses processes that selectively receive messages, and therefore |
919 | Erlang uses processes that selectively receive messages out of order, and |
813 | needs a queue. AEMP is event based, queuing messages would serve no |
920 | therefore needs a queue. AEMP is event based, queuing messages would serve |
814 | useful purpose. For the same reason the pattern-matching abilities of |
921 | no useful purpose. For the same reason the pattern-matching abilities |
815 | AnyEvent::MP are more limited, as there is little need to be able to |
922 | of AnyEvent::MP are more limited, as there is little need to be able to |
816 | filter messages without dequeuing them. |
923 | filter messages without dequeuing them. |
817 | |
924 | |
818 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
925 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
|
|
926 | being event-based, while Erlang is process-based. |
|
|
927 | |
|
|
928 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
|
|
929 | top of AEMP and Coro threads. |
819 | |
930 | |
820 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
931 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
821 | |
932 | |
822 | Sending messages in Erlang is synchronous and blocks the process (and |
933 | Sending messages in Erlang is synchronous and blocks the process until |
|
|
934 | a conenction has been established and the message sent (and so does not |
823 | so does not need a queue that can overflow). AEMP sends are immediate, |
935 | need a queue that can overflow). AEMP sends return immediately, connection |
824 | connection establishment is handled in the background. |
936 | establishment is handled in the background. |
825 | |
937 | |
826 | =item * Erlang suffers from silent message loss, AEMP does not. |
938 | =item * Erlang suffers from silent message loss, AEMP does not. |
827 | |
939 | |
828 | Erlang implements few guarantees on messages delivery - messages can get |
940 | Erlang implements few guarantees on messages delivery - messages can get |
829 | lost without any of the processes realising it (i.e. you send messages a, |
941 | lost without any of the processes realising it (i.e. you send messages a, |
830 | b, and c, and the other side only receives messages a and c). |
942 | b, and c, and the other side only receives messages a and c). |
831 | |
943 | |
832 | AEMP guarantees correct ordering, and the guarantee that after one message |
944 | AEMP guarantees (modulo hardware errors) correct ordering, and the |
833 | is lost, all following ones sent to the same port are lost as well, until |
945 | guarantee that after one message is lost, all following ones sent to the |
834 | monitoring raises an error, so there are no silent "holes" in the message |
946 | same port are lost as well, until monitoring raises an error, so there are |
835 | sequence. |
947 | no silent "holes" in the message sequence. |
|
|
948 | |
|
|
949 | If you want your software to be very reliable, you have to cope with |
|
|
950 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
|
|
951 | simply tries to work better in common error cases, such as when a network |
|
|
952 | link goes down. |
836 | |
953 | |
837 | =item * Erlang can send messages to the wrong port, AEMP does not. |
954 | =item * Erlang can send messages to the wrong port, AEMP does not. |
838 | |
955 | |
839 | In Erlang it is quite likely that a node that restarts reuses a process ID |
956 | In Erlang it is quite likely that a node that restarts reuses an Erlang |
840 | known to other nodes for a completely different process, causing messages |
957 | process ID known to other nodes for a completely different process, |
841 | destined for that process to end up in an unrelated process. |
958 | causing messages destined for that process to end up in an unrelated |
|
|
959 | process. |
842 | |
960 | |
843 | AEMP never reuses port IDs, so old messages or old port IDs floating |
961 | AEMP does not reuse port IDs, so old messages or old port IDs floating |
844 | around in the network will not be sent to an unrelated port. |
962 | around in the network will not be sent to an unrelated port. |
845 | |
963 | |
846 | =item * Erlang uses unprotected connections, AEMP uses secure |
964 | =item * Erlang uses unprotected connections, AEMP uses secure |
847 | authentication and can use TLS. |
965 | authentication and can use TLS. |
848 | |
966 | |
… | |
… | |
851 | |
969 | |
852 | =item * The AEMP protocol is optimised for both text-based and binary |
970 | =item * The AEMP protocol is optimised for both text-based and binary |
853 | communications. |
971 | communications. |
854 | |
972 | |
855 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
973 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
856 | language independent text-only protocols (good for debugging) and binary, |
974 | language independent text-only protocols (good for debugging), and binary, |
857 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
975 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
858 | used, the protocol is actually completely text-based. |
976 | used, the protocol is actually completely text-based. |
859 | |
977 | |
860 | It has also been carefully designed to be implementable in other languages |
978 | It has also been carefully designed to be implementable in other languages |
861 | with a minimum of work while gracefully degrading functionality to make the |
979 | with a minimum of work while gracefully degrading functionality to make the |
862 | protocol simple. |
980 | protocol simple. |
863 | |
981 | |
864 | =item * AEMP has more flexible monitoring options than Erlang. |
982 | =item * AEMP has more flexible monitoring options than Erlang. |
865 | |
983 | |
866 | In Erlang, you can chose to receive I<all> exit signals as messages |
984 | In Erlang, you can chose to receive I<all> exit signals as messages or |
867 | or I<none>, there is no in-between, so monitoring single processes is |
985 | I<none>, there is no in-between, so monitoring single Erlang processes is |
868 | difficult to implement. Monitoring in AEMP is more flexible than in |
986 | difficult to implement. |
869 | Erlang, as one can choose between automatic kill, exit message or callback |
987 | |
870 | on a per-process basis. |
988 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
|
|
989 | between automatic kill, exit message or callback on a per-port basis. |
871 | |
990 | |
872 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
991 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
873 | |
992 | |
874 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
993 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
875 | same way as linking is (except linking is unreliable in Erlang). |
994 | same way as linking is (except linking is unreliable in Erlang). |
… | |
… | |
897 | overhead, as well as having to keep a proxy object everywhere. |
1016 | overhead, as well as having to keep a proxy object everywhere. |
898 | |
1017 | |
899 | Strings can easily be printed, easily serialised etc. and need no special |
1018 | Strings can easily be printed, easily serialised etc. and need no special |
900 | procedures to be "valid". |
1019 | procedures to be "valid". |
901 | |
1020 | |
902 | And as a result, a miniport consists of a single closure stored in a |
1021 | And as a result, a port with just a default receiver consists of a single |
903 | global hash - it can't become much cheaper. |
1022 | code reference stored in a global hash - it can't become much cheaper. |
904 | |
1023 | |
905 | =item Why favour JSON, why not a real serialising format such as Storable? |
1024 | =item Why favour JSON, why not a real serialising format such as Storable? |
906 | |
1025 | |
907 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
1026 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
908 | format, but currently there is no way to make a node use Storable by |
1027 | format, but currently there is no way to make a node use Storable by |
… | |
… | |
924 | |
1043 | |
925 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1044 | L<AnyEvent::MP::Intro> - a gentle introduction. |
926 | |
1045 | |
927 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1046 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
928 | |
1047 | |
929 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
1048 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
930 | your applications. |
1049 | your applications. |
|
|
1050 | |
|
|
1051 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
931 | |
1052 | |
932 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
1053 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
933 | all nodes. |
1054 | all nodes. |
934 | |
1055 | |
935 | L<AnyEvent>. |
1056 | L<AnyEvent>. |