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8 | |
8 | |
9 | $NODE # contains this node's noderef |
9 | $NODE # contains this node's noderef |
10 | NODE # returns this node's noderef |
10 | NODE # returns this node's noderef |
11 | NODE $port # returns the noderef of the port |
11 | NODE $port # returns the noderef of the port |
12 | |
12 | |
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13 | $SELF # receiving/own port id in rcv callbacks |
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14 | |
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15 | # ports are message endpoints |
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16 | |
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17 | # sending messages |
13 | snd $port, type => data...; |
18 | snd $port, type => data...; |
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19 | snd $port, @msg; |
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20 | snd @msg_with_first_element_being_a_port; |
14 | |
21 | |
15 | $SELF # receiving/own port id in rcv callbacks |
22 | # miniports |
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23 | my $miniport = port { my @msg = @_; 0 }; |
16 | |
24 | |
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25 | # full ports |
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26 | my $port = port; |
17 | rcv $port, smartmatch => $cb->($port, @msg); |
27 | rcv $port, smartmatch => $cb->(@msg); |
18 | |
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19 | # examples: |
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20 | rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; |
28 | rcv $port, ping => sub { snd $_[0], "pong"; 0 }; |
21 | rcv $port1, pong => sub { warn "pong received\n" }; |
29 | rcv $port, pong => sub { warn "pong received\n"; 0 }; |
22 | snd $port2, ping => $port1; |
30 | |
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31 | # remote ports |
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32 | my $port = spawn $node, $initfunc, @initdata; |
23 | |
33 | |
24 | # more, smarter, matches (_any_ is exported by this module) |
34 | # more, smarter, matches (_any_ is exported by this module) |
25 | rcv $port, [child_died => $pid] => sub { ... |
35 | rcv $port, [child_died => $pid] => sub { ... |
26 | rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 |
36 | rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 |
27 | |
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28 | # linking two ports, so they both crash together |
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29 | lnk $port1, $port2; |
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30 | |
37 | |
31 | # monitoring |
38 | # monitoring |
32 | mon $port, $cb->(@msg) # callback is invoked on death |
39 | mon $port, $cb->(@msg) # callback is invoked on death |
33 | mon $port, $otherport # kill otherport on abnormal death |
40 | mon $port, $otherport # kill otherport on abnormal death |
34 | mon $port, $otherport, @msg # send message on death |
41 | mon $port, $otherport, @msg # send message on death |
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… | |
112 | |
119 | |
113 | our $VERSION = '0.1'; |
120 | our $VERSION = '0.1'; |
114 | our @EXPORT = qw( |
121 | our @EXPORT = qw( |
115 | NODE $NODE *SELF node_of _any_ |
122 | NODE $NODE *SELF node_of _any_ |
116 | resolve_node initialise_node |
123 | resolve_node initialise_node |
117 | snd rcv mon kil reg psub |
124 | snd rcv mon kil reg psub spawn |
118 | port |
125 | port |
119 | ); |
126 | ); |
120 | |
127 | |
121 | our $SELF; |
128 | our $SELF; |
122 | |
129 | |
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343 | registered. |
350 | registered. |
344 | |
351 | |
345 | The global C<$SELF> (exported by this module) contains C<$port> while |
352 | The global C<$SELF> (exported by this module) contains C<$port> while |
346 | executing the callback. |
353 | executing the callback. |
347 | |
354 | |
348 | Runtime errors wdurign callback execution will result in the port being |
355 | Runtime errors during callback execution will result in the port being |
349 | C<kil>ed. |
356 | C<kil>ed. |
350 | |
357 | |
351 | If the match is an array reference, then it will be matched against the |
358 | If the match is an array reference, then it will be matched against the |
352 | first elements of the message, otherwise only the first element is being |
359 | first elements of the message, otherwise only the first element is being |
353 | matched. |
360 | matched. |
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513 | C<$rvport> defaults to C<$SELF>. |
520 | C<$rvport> defaults to C<$SELF>. |
514 | |
521 | |
515 | In the last form (message), a message of the form C<@msg, @reason> will be |
522 | In the last form (message), a message of the form C<@msg, @reason> will be |
516 | C<snd>. |
523 | C<snd>. |
517 | |
524 | |
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525 | As a rule of thumb, monitoring requests should always monitor a port from |
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526 | a local port (or callback). The reason is that kill messages might get |
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527 | lost, just like any other message. Another less obvious reason is that |
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528 | even monitoring requests can get lost (for exmaple, when the connection |
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529 | to the other node goes down permanently). When monitoring a port locally |
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530 | these problems do not exist. |
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531 | |
518 | Example: call a given callback when C<$port> is killed. |
532 | Example: call a given callback when C<$port> is killed. |
519 | |
533 | |
520 | mon $port, sub { warn "port died because of <@_>\n" }; |
534 | mon $port, sub { warn "port died because of <@_>\n" }; |
521 | |
535 | |
522 | Example: kill ourselves when C<$port> is killed abnormally. |
536 | Example: kill ourselves when C<$port> is killed abnormally. |
… | |
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578 | #TODO: mon-less form? |
592 | #TODO: mon-less form? |
579 | |
593 | |
580 | mon $port, sub { 0 && @refs } |
594 | mon $port, sub { 0 && @refs } |
581 | } |
595 | } |
582 | |
596 | |
583 | =item lnk $port1, $port2 |
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584 | |
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585 | =item lnk $otherport |
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586 | |
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587 | Link two ports. This is simply a shorthand for: |
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588 | |
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589 | mon $port1, $port2; |
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590 | mon $port2, $port1; |
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591 | |
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592 | It means that if either one is killed abnormally, the other one gets |
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593 | killed as well. |
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594 | |
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595 | The one-argument form assumes that one port is C<$SELF>. |
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596 | |
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597 | =cut |
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598 | |
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599 | sub lnk { |
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600 | my $port1 = shift; |
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601 | my $port2 = @_ ? shift : $SELF || Carp::croak 'lnk: called with one argument only, but $SELF not set,'; |
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602 | |
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603 | mon $port1, $port2; |
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604 | mon $port2, $port1; |
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605 | } |
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606 | |
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607 | =item kil $port[, @reason] |
597 | =item kil $port[, @reason] |
608 | |
598 | |
609 | Kill the specified port with the given C<@reason>. |
599 | Kill the specified port with the given C<@reason>. |
610 | |
600 | |
611 | If no C<@reason> is specified, then the port is killed "normally" (linked |
601 | If no C<@reason> is specified, then the port is killed "normally" (linked |
… | |
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617 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
607 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
618 | will be reported as reason C<< die => $@ >>. |
608 | will be reported as reason C<< die => $@ >>. |
619 | |
609 | |
620 | Transport/communication errors are reported as C<< transport_error => |
610 | Transport/communication errors are reported as C<< transport_error => |
621 | $message >>. |
611 | $message >>. |
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612 | |
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613 | =cut |
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614 | |
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615 | =item $port = spawn $node, $initfunc[, @initdata] |
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616 | |
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617 | Creates a port on the node C<$node> (which can also be a port ID, in which |
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618 | case it's the node where that port resides). |
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619 | |
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620 | The port ID of the newly created port is return immediately, and it is |
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621 | permissible to immediately start sending messages or monitor the port. |
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622 | |
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623 | After the port has been created, the init function is |
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624 | called. This function must be a fully-qualified function name |
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625 | (e.g. C<MyApp::Chat::Server::init>). To specify a function in the main |
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626 | program, use C<::name>. |
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627 | |
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628 | If the function doesn't exist, then the node tries to C<require> |
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629 | the package, then the package above the package and so on (e.g. |
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630 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
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631 | exists or it runs out of package names. |
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632 | |
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633 | The init function is then called with the newly-created port as context |
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634 | object (C<$SELF>) and the C<@initdata> values as arguments. |
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635 | |
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636 | A common idiom is to pass your own port, monitor the spawned port, and |
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637 | in the init function, monitor the original port. This two-way monitoring |
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638 | ensures that both ports get cleaned up when there is a problem. |
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639 | |
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640 | Example: spawn a chat server port on C<$othernode>. |
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641 | |
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642 | # this node, executed from within a port context: |
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643 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
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644 | mon $server; |
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645 | |
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646 | # init function on C<$othernode> |
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647 | sub connect { |
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648 | my ($srcport) = @_; |
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649 | |
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650 | mon $srcport; |
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651 | |
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652 | rcv $SELF, sub { |
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653 | ... |
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654 | }; |
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655 | } |
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656 | |
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657 | =cut |
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658 | |
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659 | sub _spawn { |
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660 | my $port = shift; |
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661 | my $init = shift; |
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662 | |
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663 | local $SELF = "$NODE#$port"; |
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664 | eval { |
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665 | &{ load_func $init } |
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666 | }; |
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667 | _self_die if $@; |
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668 | } |
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669 | |
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670 | sub spawn(@) { |
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671 | my ($noderef, undef) = split /#/, shift, 2; |
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672 | |
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673 | my $id = "$RUNIQ." . $ID++; |
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674 | |
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675 | $_[0] =~ /::/ |
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676 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
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677 | |
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678 | ($NODE{$noderef} || add_node $noderef) |
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679 | ->send (["", "AnyEvent::MP::_spawn" => $id, @_]); |
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680 | |
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681 | "$noderef#$id" |
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682 | } |
622 | |
683 | |
623 | =back |
684 | =back |
624 | |
685 | |
625 | =head1 NODE MESSAGES |
686 | =head1 NODE MESSAGES |
626 | |
687 | |
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759 | or I<none>, there is no in-between, so monitoring single processes is |
820 | or I<none>, there is no in-between, so monitoring single processes is |
760 | difficult to implement. Monitoring in AEMP is more flexible than in |
821 | difficult to implement. Monitoring in AEMP is more flexible than in |
761 | Erlang, as one can choose between automatic kill, exit message or callback |
822 | Erlang, as one can choose between automatic kill, exit message or callback |
762 | on a per-process basis. |
823 | on a per-process basis. |
763 | |
824 | |
764 | =item * Erlang has different semantics for monitoring and linking, AEMP has the same. |
825 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
765 | |
826 | |
766 | Monitoring in Erlang is not an indicator of process death/crashes, |
827 | Monitoring in Erlang is not an indicator of process death/crashes, |
767 | as linking is (except linking is unreliable in Erlang). In AEMP, the |
828 | as linking is (except linking is unreliable in Erlang). |
768 | semantics of monitoring and linking are identical, linking is simply |
829 | |
769 | two-way monitoring with automatic kill. |
830 | In AEMP, you don't "look up" registered port names or send to named ports |
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831 | that might or might not be persistent. Instead, you normally spawn a port |
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832 | on the remote node. The init function monitors the you, and you monitor |
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833 | the remote port. Since both monitors are local to the node, they are much |
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834 | more reliable. |
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835 | |
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836 | This also saves round-trips and avoids sending messages to the wrong port |
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837 | (hard to do in Erlang). |
770 | |
838 | |
771 | =back |
839 | =back |
772 | |
840 | |
773 | =head1 SEE ALSO |
841 | =head1 SEE ALSO |
774 | |
842 | |