1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent::MP - multi-processing/message-passing framework |
3 | AnyEvent::MP - erlang-style multi-processing/message-passing framework |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use AnyEvent::MP; |
7 | use AnyEvent::MP; |
8 | |
8 | |
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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 | |
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35 | # destroy a prot again |
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36 | kil $port; # "normal" kill |
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37 | kil $port, my_error => "everything is broken"; # error kill |
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38 | |
35 | # monitoring |
39 | # monitoring |
36 | mon $port, $cb->(@msg) # callback is invoked on death |
40 | mon $localport, $cb->(@msg) # callback is invoked on death |
37 | mon $port, $otherport # kill otherport on abnormal death |
41 | mon $localport, $otherport # kill otherport on abnormal death |
38 | mon $port, $otherport, @msg # send message on death |
42 | mon $localport, $otherport, @msg # send message on death |
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43 | |
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44 | # temporarily execute code in port context |
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45 | peval $port, sub { die "kill the port!" }; |
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46 | |
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47 | # execute callbacks in $SELF port context |
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48 | my $timer = AE::timer 1, 0, psub { |
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49 | die "kill the port, delayed"; |
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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. |
44 | AnyEvent::MP::Intro - explains most concepts. |
56 | AnyEvent::MP::Intro - explains most concepts. |
45 | AnyEvent::MP::Kernel - mostly stable. |
57 | AnyEvent::MP::Kernel - mostly stable API. |
46 | AnyEvent::MP::Global - stable but incomplete, protocol not yet final. |
58 | AnyEvent::MP::Global - stable API. |
47 | |
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48 | stay tuned. |
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49 | |
59 | |
50 | =head1 DESCRIPTION |
60 | =head1 DESCRIPTION |
51 | |
61 | |
52 | This module (-family) implements a simple message passing framework. |
62 | This module (-family) implements a simple message passing framework. |
53 | |
63 | |
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118 | seed node that blocks for long periods will slow down everybody else. |
128 | seed node that blocks for long periods will slow down everybody else. |
119 | |
129 | |
120 | =item seeds - C<host:port> |
130 | =item seeds - C<host:port> |
121 | |
131 | |
122 | Seeds are transport endpoint(s) (usually a hostname/IP address and a |
132 | Seeds are transport endpoint(s) (usually a hostname/IP address and a |
123 | TCP port) of nodes thta should be used as seed nodes. |
133 | TCP port) of nodes that should be used as seed nodes. |
124 | |
134 | |
125 | The nodes listening on those endpoints are expected to be long-running, |
135 | The nodes listening on those endpoints are expected to be long-running, |
126 | and at least one of those should always be available. When nodes run out |
136 | and at least one of those should always be available. When nodes run out |
127 | of connections (e.g. due to a network error), they try to re-establish |
137 | of connections (e.g. due to a network error), they try to re-establish |
128 | connections to some seednodes again to join the network. |
138 | connections to some seednodes again to join the network. |
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145 | |
155 | |
146 | use AE (); |
156 | use AE (); |
147 | |
157 | |
148 | use base "Exporter"; |
158 | use base "Exporter"; |
149 | |
159 | |
150 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
160 | our $VERSION = 1.22; |
151 | |
161 | |
152 | our @EXPORT = qw( |
162 | our @EXPORT = qw( |
153 | NODE $NODE *SELF node_of after |
163 | NODE $NODE *SELF node_of after |
154 | configure |
164 | configure |
155 | snd rcv mon mon_guard kil reg psub spawn |
165 | snd rcv mon mon_guard kil psub peval spawn cal |
156 | port |
166 | port |
157 | ); |
167 | ); |
158 | |
168 | |
159 | our $SELF; |
169 | our $SELF; |
160 | |
170 | |
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229 | L<AnyEvent::MP::Global> module, which will then use it to keep |
239 | L<AnyEvent::MP::Global> module, which will then use it to keep |
230 | connectivity with at least one node at any point in time. |
240 | connectivity with at least one node at any point in time. |
231 | |
241 | |
232 | =back |
242 | =back |
233 | |
243 | |
234 | Example: become a distributed node using the locla node name as profile. |
244 | Example: become a distributed node using the local node name as profile. |
235 | This should be the most common form of invocation for "daemon"-type nodes. |
245 | This should be the most common form of invocation for "daemon"-type nodes. |
236 | |
246 | |
237 | configure |
247 | configure |
238 | |
248 | |
239 | Example: become an anonymous node. This form is often used for commandline |
249 | Example: become an anonymous node. This form is often used for commandline |
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373 | msg1 => sub { ... }, |
383 | msg1 => sub { ... }, |
374 | ... |
384 | ... |
375 | ; |
385 | ; |
376 | |
386 | |
377 | Example: temporarily register a rcv callback for a tag matching some port |
387 | Example: temporarily register a rcv callback for a tag matching some port |
378 | (e.g. for a rpc reply) and unregister it after a message was received. |
388 | (e.g. for an rpc reply) and unregister it after a message was received. |
379 | |
389 | |
380 | rcv $port, $otherport => sub { |
390 | rcv $port, $otherport => sub { |
381 | my @reply = @_; |
391 | my @reply = @_; |
382 | |
392 | |
383 | rcv $SELF, $otherport; |
393 | rcv $SELF, $otherport; |
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396 | if (ref $_[0]) { |
406 | if (ref $_[0]) { |
397 | if (my $self = $PORT_DATA{$portid}) { |
407 | if (my $self = $PORT_DATA{$portid}) { |
398 | "AnyEvent::MP::Port" eq ref $self |
408 | "AnyEvent::MP::Port" eq ref $self |
399 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
409 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
400 | |
410 | |
401 | $self->[2] = shift; |
411 | $self->[0] = shift; |
402 | } else { |
412 | } else { |
403 | my $cb = shift; |
413 | my $cb = shift; |
404 | $PORT{$portid} = sub { |
414 | $PORT{$portid} = sub { |
405 | local $SELF = $port; |
415 | local $SELF = $port; |
406 | eval { &$cb }; _self_die if $@; |
416 | eval { &$cb }; _self_die if $@; |
407 | }; |
417 | }; |
408 | } |
418 | } |
409 | } elsif (defined $_[0]) { |
419 | } elsif (defined $_[0]) { |
410 | my $self = $PORT_DATA{$portid} ||= do { |
420 | my $self = $PORT_DATA{$portid} ||= do { |
411 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
421 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
412 | |
422 | |
413 | $PORT{$portid} = sub { |
423 | $PORT{$portid} = sub { |
414 | local $SELF = $port; |
424 | local $SELF = $port; |
415 | |
425 | |
416 | if (my $cb = $self->[1]{$_[0]}) { |
426 | if (my $cb = $self->[1]{$_[0]}) { |
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438 | } |
448 | } |
439 | |
449 | |
440 | $port |
450 | $port |
441 | } |
451 | } |
442 | |
452 | |
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453 | =item peval $port, $coderef[, @args] |
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454 | |
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455 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
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456 | when the code throews an exception the C<$port> will be killed. |
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457 | |
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458 | Any remaining args will be passed to the callback. Any return values will |
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459 | be returned to the caller. |
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460 | |
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461 | This is useful when you temporarily want to execute code in the context of |
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462 | a port. |
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463 | |
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464 | Example: create a port and run some initialisation code in it's context. |
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465 | |
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466 | my $port = port { ... }; |
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467 | |
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468 | peval $port, sub { |
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469 | init |
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470 | or die "unable to init"; |
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471 | }; |
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472 | |
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473 | =cut |
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474 | |
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475 | sub peval($$) { |
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476 | local $SELF = shift; |
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477 | my $cb = shift; |
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478 | |
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479 | if (wantarray) { |
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480 | my @res = eval { &$cb }; |
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481 | _self_die if $@; |
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482 | @res |
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483 | } else { |
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484 | my $res = eval { &$cb }; |
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485 | _self_die if $@; |
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486 | $res |
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487 | } |
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488 | } |
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489 | |
443 | =item $closure = psub { BLOCK } |
490 | =item $closure = psub { BLOCK } |
444 | |
491 | |
445 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
492 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
446 | closure is executed, sets up the environment in the same way as in C<rcv> |
493 | closure is executed, sets up the environment in the same way as in C<rcv> |
447 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
494 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
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495 | |
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496 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
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497 | BLOCK } } >>. |
448 | |
498 | |
449 | This is useful when you register callbacks from C<rcv> callbacks: |
499 | This is useful when you register callbacks from C<rcv> callbacks: |
450 | |
500 | |
451 | rcv delayed_reply => sub { |
501 | rcv delayed_reply => sub { |
452 | my ($delay, @reply) = @_; |
502 | my ($delay, @reply) = @_; |
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525 | delivered again. |
575 | delivered again. |
526 | |
576 | |
527 | Inter-host-connection timeouts and monitoring depend on the transport |
577 | Inter-host-connection timeouts and monitoring depend on the transport |
528 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
578 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
529 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
579 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
530 | non-idle connection, and usually around two hours for idle conenctions). |
580 | non-idle connection, and usually around two hours for idle connections). |
531 | |
581 | |
532 | This means that monitoring is good for program errors and cleaning up |
582 | This means that monitoring is good for program errors and cleaning up |
533 | stuff eventually, but they are no replacement for a timeout when you need |
583 | stuff eventually, but they are no replacement for a timeout when you need |
534 | to ensure some maximum latency. |
584 | to ensure some maximum latency. |
535 | |
585 | |
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567 | } |
617 | } |
568 | |
618 | |
569 | $node->monitor ($port, $cb); |
619 | $node->monitor ($port, $cb); |
570 | |
620 | |
571 | defined wantarray |
621 | defined wantarray |
572 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
622 | and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) |
573 | } |
623 | } |
574 | |
624 | |
575 | =item $guard = mon_guard $port, $ref, $ref... |
625 | =item $guard = mon_guard $port, $ref, $ref... |
576 | |
626 | |
577 | Monitors the given C<$port> and keeps the passed references. When the port |
627 | Monitors the given C<$port> and keeps the passed references. When the port |
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715 | ? $action[0]() |
765 | ? $action[0]() |
716 | : snd @action; |
766 | : snd @action; |
717 | }; |
767 | }; |
718 | } |
768 | } |
719 | |
769 | |
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770 | =item cal $port, @msg, $callback[, $timeout] |
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771 | |
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772 | A simple form of RPC - sends a message to the given C<$port> with the |
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773 | given contents (C<@msg>), but adds a reply port to the message. |
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774 | |
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775 | The reply port is created temporarily just for the purpose of receiving |
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776 | the reply, and will be C<kil>ed when no longer needed. |
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777 | |
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778 | A reply message sent to the port is passed to the C<$callback> as-is. |
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779 | |
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780 | If an optional time-out (in seconds) is given and it is not C<undef>, |
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781 | then the callback will be called without any arguments after the time-out |
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782 | elapsed and the port is C<kil>ed. |
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783 | |
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784 | If no time-out is given (or it is C<undef>), then the local port will |
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785 | monitor the remote port instead, so it eventually gets cleaned-up. |
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786 | |
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787 | Currently this function returns the temporary port, but this "feature" |
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788 | might go in future versions unless you can make a convincing case that |
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789 | this is indeed useful for something. |
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790 | |
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791 | =cut |
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792 | |
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793 | sub cal(@) { |
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794 | my $timeout = ref $_[-1] ? undef : pop; |
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795 | my $cb = pop; |
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796 | |
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797 | my $port = port { |
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798 | undef $timeout; |
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799 | kil $SELF; |
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800 | &$cb; |
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801 | }; |
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802 | |
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803 | if (defined $timeout) { |
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804 | $timeout = AE::timer $timeout, 0, sub { |
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805 | undef $timeout; |
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806 | kil $port; |
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807 | $cb->(); |
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808 | }; |
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809 | } else { |
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810 | mon $_[0], sub { |
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811 | kil $port; |
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812 | $cb->(); |
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813 | }; |
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814 | } |
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815 | |
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816 | push @_, $port; |
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817 | &snd; |
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818 | |
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819 | $port |
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820 | } |
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821 | |
720 | =back |
822 | =back |
721 | |
823 | |
722 | =head1 AnyEvent::MP vs. Distributed Erlang |
824 | =head1 AnyEvent::MP vs. Distributed Erlang |
723 | |
825 | |
724 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
826 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
725 | == aemp node, Erlang process == aemp port), so many of the documents and |
827 | == aemp node, Erlang process == aemp port), so many of the documents and |
726 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
828 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
727 | sample: |
829 | sample: |
728 | |
830 | |
729 | http://www.Erlang.se/doc/programming_rules.shtml |
831 | http://www.erlang.se/doc/programming_rules.shtml |
730 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
832 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
731 | http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6 |
833 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
732 | http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
834 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
733 | |
835 | |
734 | Despite the similarities, there are also some important differences: |
836 | Despite the similarities, there are also some important differences: |
735 | |
837 | |
736 | =over 4 |
838 | =over 4 |
737 | |
839 | |
738 | =item * Node IDs are arbitrary strings in AEMP. |
840 | =item * Node IDs are arbitrary strings in AEMP. |
739 | |
841 | |
740 | Erlang relies on special naming and DNS to work everywhere in the same |
842 | Erlang relies on special naming and DNS to work everywhere in the same |
741 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
843 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
742 | configuration or DNS), but will otherwise discover other odes itself. |
844 | configuration or DNS), and possibly the addresses of some seed nodes, but |
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845 | will otherwise discover other nodes (and their IDs) itself. |
743 | |
846 | |
744 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
847 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
745 | uses "local ports are like remote ports". |
848 | uses "local ports are like remote ports". |
746 | |
849 | |
747 | The failure modes for local ports are quite different (runtime errors |
850 | The failure modes for local ports are quite different (runtime errors |
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772 | so does not need a queue that can overflow). AEMP sends are immediate, |
875 | so does not need a queue that can overflow). AEMP sends are immediate, |
773 | connection establishment is handled in the background. |
876 | connection establishment is handled in the background. |
774 | |
877 | |
775 | =item * Erlang suffers from silent message loss, AEMP does not. |
878 | =item * Erlang suffers from silent message loss, AEMP does not. |
776 | |
879 | |
777 | Erlang makes few guarantees on messages delivery - messages can get lost |
880 | Erlang implements few guarantees on messages delivery - messages can get |
778 | without any of the processes realising it (i.e. you send messages a, b, |
881 | lost without any of the processes realising it (i.e. you send messages a, |
779 | and c, and the other side only receives messages a and c). |
882 | b, and c, and the other side only receives messages a and c). |
780 | |
883 | |
781 | AEMP guarantees correct ordering, and the guarantee that after one message |
884 | AEMP guarantees correct ordering, and the guarantee that after one message |
782 | is lost, all following ones sent to the same port are lost as well, until |
885 | is lost, all following ones sent to the same port are lost as well, until |
783 | monitoring raises an error, so there are no silent "holes" in the message |
886 | monitoring raises an error, so there are no silent "holes" in the message |
784 | sequence. |
887 | sequence. |