… | |
… | |
35 | # destroy a port 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 $port, $cb->(@msg) # callback is invoked on death |
41 | mon $localport, $otherport # kill otherport on abnormal death |
41 | mon $port, $localport # kill localport on abnormal death |
42 | mon $localport, $otherport, @msg # send message on death |
42 | mon $port, $localport, @msg # send message on death |
43 | |
43 | |
44 | # temporarily execute code in port context |
44 | # temporarily execute code in port context |
45 | peval $port, sub { die "kill the port!" }; |
45 | peval $port, sub { die "kill the port!" }; |
46 | |
46 | |
47 | # execute callbacks in $SELF port context |
47 | # execute callbacks in $SELF port context |
48 | my $timer = AE::timer 1, 0, psub { |
48 | my $timer = AE::timer 1, 0, psub { |
49 | die "kill the port, delayed"; |
49 | die "kill the port, delayed"; |
50 | }; |
50 | }; |
51 | |
51 | |
52 | =head1 CURRENT STATUS |
52 | # distributed database - modification |
|
|
53 | db_set $family => $subkey [=> $value] # add a subkey |
|
|
54 | db_del $family => $subkey... # delete one or more subkeys |
|
|
55 | db_reg $family => $port [=> $value] # register a port |
53 | |
56 | |
54 | bin/aemp - stable. |
57 | # distributed database - queries |
55 | AnyEvent::MP - stable API, should work. |
58 | db_family $family => $cb->(\%familyhash) |
56 | AnyEvent::MP::Intro - explains most concepts. |
59 | db_keys $family => $cb->(\@keys) |
57 | AnyEvent::MP::Kernel - mostly stable API. |
60 | db_values $family => $cb->(\@values) |
58 | AnyEvent::MP::Global - stable API. |
61 | |
|
|
62 | # distributed database - monitoring a family |
|
|
63 | db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted) |
59 | |
64 | |
60 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
61 | |
66 | |
62 | This module (-family) implements a simple message passing framework. |
67 | This module (-family) implements a simple message passing framework. |
63 | |
68 | |
… | |
… | |
113 | each other. To do this, nodes should listen on one or more local transport |
118 | each other. To do this, nodes should listen on one or more local transport |
114 | endpoints - binds. |
119 | endpoints - binds. |
115 | |
120 | |
116 | Currently, only standard C<ip:port> specifications can be used, which |
121 | Currently, only standard C<ip:port> specifications can be used, which |
117 | specify TCP ports to listen on. So a bind is basically just a tcp socket |
122 | specify TCP ports to listen on. So a bind is basically just a tcp socket |
118 | in listening mode thta accepts conenctions form other nodes. |
123 | in listening mode that accepts connections from other nodes. |
119 | |
124 | |
120 | =item seed nodes |
125 | =item seed nodes |
121 | |
126 | |
122 | When a node starts, it knows nothing about the network it is in - it |
127 | When a node starts, it knows nothing about the network it is in - it |
123 | needs to connect to at least one other node that is already in the |
128 | needs to connect to at least one other node that is already in the |
124 | network. These other nodes are called "seed nodes". |
129 | network. These other nodes are called "seed nodes". |
125 | |
130 | |
126 | Seed nodes themselves are not special - they are seed nodes only because |
131 | Seed nodes themselves are not special - they are seed nodes only because |
127 | some other node I<uses> them as such, but any node can be used as seed |
132 | some other node I<uses> them as such, but any node can be used as seed |
128 | node for other nodes, and eahc node cna use a different set of seed nodes. |
133 | node for other nodes, and eahc node can use a different set of seed nodes. |
129 | |
134 | |
130 | In addition to discovering the network, seed nodes are also used to |
135 | In addition to discovering the network, seed nodes are also used to |
131 | maintain the network - all nodes using the same seed node form are part of |
136 | maintain the network - all nodes using the same seed node are part of the |
132 | the same network. If a network is split into multiple subnets because e.g. |
137 | same network. If a network is split into multiple subnets because e.g. the |
133 | the network link between the parts goes down, then using the same seed |
138 | network link between the parts goes down, then using the same seed nodes |
134 | nodes for all nodes ensures that eventually the subnets get merged again. |
139 | for all nodes ensures that eventually the subnets get merged again. |
135 | |
140 | |
136 | Seed nodes are expected to be long-running, and at least one seed node |
141 | Seed nodes are expected to be long-running, and at least one seed node |
137 | should always be available. They should also be relatively responsive - a |
142 | should always be available. They should also be relatively responsive - a |
138 | seed node that blocks for long periods will slow down everybody else. |
143 | seed node that blocks for long periods will slow down everybody else. |
139 | |
144 | |
… | |
… | |
163 | |
168 | |
164 | Any node that loads the L<AnyEvent::MP::Global> module becomes a global |
169 | Any node that loads the L<AnyEvent::MP::Global> module becomes a global |
165 | node and tries to keep connections to all other nodes. So while it can |
170 | node and tries to keep connections to all other nodes. So while it can |
166 | make sense to make every node "global" in small networks, it usually makes |
171 | make sense to make every node "global" in small networks, it usually makes |
167 | sense to only make seed nodes into global nodes in large networks (nodes |
172 | sense to only make seed nodes into global nodes in large networks (nodes |
168 | keep connections to seed nodes and global nodes, so makign them the same |
173 | keep connections to seed nodes and global nodes, so making them the same |
169 | reduces overhead). |
174 | reduces overhead). |
170 | |
175 | |
171 | =back |
176 | =back |
172 | |
177 | |
173 | =head1 VARIABLES/FUNCTIONS |
178 | =head1 VARIABLES/FUNCTIONS |
… | |
… | |
178 | |
183 | |
179 | package AnyEvent::MP; |
184 | package AnyEvent::MP; |
180 | |
185 | |
181 | use AnyEvent::MP::Config (); |
186 | use AnyEvent::MP::Config (); |
182 | use AnyEvent::MP::Kernel; |
187 | use AnyEvent::MP::Kernel; |
183 | use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID); |
188 | use AnyEvent::MP::Kernel qw( |
|
|
189 | %NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID |
|
|
190 | add_node load_func |
|
|
191 | |
|
|
192 | NODE $NODE |
|
|
193 | configure |
|
|
194 | node_of port_is_local |
|
|
195 | snd kil |
|
|
196 | db_set db_del |
|
|
197 | db_mon db_family db_keys db_values |
|
|
198 | ); |
184 | |
199 | |
185 | use common::sense; |
200 | use common::sense; |
186 | |
201 | |
187 | use Carp (); |
202 | use Carp (); |
188 | |
203 | |
189 | use AE (); |
204 | use AnyEvent (); |
190 | use Guard (); |
205 | use Guard (); |
191 | |
206 | |
192 | use base "Exporter"; |
207 | use base "Exporter"; |
193 | |
208 | |
194 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
209 | our $VERSION = '2.02'; # also in MP/Config.pm |
195 | |
210 | |
196 | our @EXPORT = qw( |
211 | our @EXPORT = qw( |
197 | NODE $NODE *SELF node_of after |
212 | NODE $NODE |
198 | configure |
213 | configure |
|
|
214 | node_of port_is_local |
|
|
215 | snd kil |
|
|
216 | db_set db_del |
|
|
217 | db_mon db_family db_keys db_values |
|
|
218 | |
|
|
219 | *SELF |
|
|
220 | |
199 | snd rcv mon mon_guard kil psub peval spawn cal |
221 | port rcv mon mon_guard psub peval spawn cal |
200 | port |
|
|
201 | db_set db_del db_reg |
222 | db_set db_del db_reg |
|
|
223 | db_mon db_family db_keys db_values |
|
|
224 | |
|
|
225 | after |
202 | ); |
226 | ); |
203 | |
227 | |
204 | our $SELF; |
228 | our $SELF; |
205 | |
229 | |
206 | sub _self_die() { |
230 | sub _self_die() { |
… | |
… | |
217 | |
241 | |
218 | =item $nodeid = node_of $port |
242 | =item $nodeid = node_of $port |
219 | |
243 | |
220 | Extracts and returns the node ID from a port ID or a node ID. |
244 | Extracts and returns the node ID from a port ID or a node ID. |
221 | |
245 | |
|
|
246 | =item $is_local = port_is_local $port |
|
|
247 | |
|
|
248 | Returns true iff the port is a local port. |
|
|
249 | |
222 | =item configure $profile, key => value... |
250 | =item configure $profile, key => value... |
223 | |
251 | |
224 | =item configure key => value... |
252 | =item configure key => value... |
225 | |
253 | |
226 | Before a node can talk to other nodes on the network (i.e. enter |
254 | Before a node can talk to other nodes on the network (i.e. enter |
… | |
… | |
237 | =over 4 |
265 | =over 4 |
238 | |
266 | |
239 | =item norc => $boolean (default false) |
267 | =item norc => $boolean (default false) |
240 | |
268 | |
241 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
269 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
242 | be consulted - all configuraiton options must be specified in the |
270 | be consulted - all configuration options must be specified in the |
243 | C<configure> call. |
271 | C<configure> call. |
244 | |
272 | |
245 | =item force => $boolean (default false) |
273 | =item force => $boolean (default false) |
246 | |
274 | |
247 | IF true, then the values specified in the C<configure> will take |
275 | IF true, then the values specified in the C<configure> will take |
248 | precedence over any values configured via the rc file. The default is for |
276 | precedence over any values configured via the rc file. The default is for |
249 | the rc file to override any options specified in the program. |
277 | the rc file to override any options specified in the program. |
250 | |
|
|
251 | =item secure => $pass->($nodeid) |
|
|
252 | |
|
|
253 | In addition to specifying a boolean, you can specify a code reference that |
|
|
254 | is called for every remote execution attempt - the execution request is |
|
|
255 | granted iff the callback returns a true value. |
|
|
256 | |
|
|
257 | See F<semp setsecure> for more info. |
|
|
258 | |
278 | |
259 | =back |
279 | =back |
260 | |
280 | |
261 | =over 4 |
281 | =over 4 |
262 | |
282 | |
… | |
… | |
291 | |
311 | |
292 | =item step 2, bind listener sockets |
312 | =item step 2, bind listener sockets |
293 | |
313 | |
294 | The next step is to look up the binds in the profile, followed by binding |
314 | The next step is to look up the binds in the profile, followed by binding |
295 | aemp protocol listeners on all binds specified (it is possible and valid |
315 | aemp protocol listeners on all binds specified (it is possible and valid |
296 | to have no binds, meaning that the node cannot be contacted form the |
316 | to have no binds, meaning that the node cannot be contacted from the |
297 | outside. This means the node cannot talk to other nodes that also have no |
317 | outside. This means the node cannot talk to other nodes that also have no |
298 | binds, but it can still talk to all "normal" nodes). |
318 | binds, but it can still talk to all "normal" nodes). |
299 | |
319 | |
300 | If the profile does not specify a binds list, then a default of C<*> is |
320 | If the profile does not specify a binds list, then a default of C<*> is |
301 | used, meaning the node will bind on a dynamically-assigned port on every |
321 | used, meaning the node will bind on a dynamically-assigned port on every |
… | |
… | |
397 | |
417 | |
398 | =cut |
418 | =cut |
399 | |
419 | |
400 | sub rcv($@); |
420 | sub rcv($@); |
401 | |
421 | |
402 | sub _kilme { |
422 | my $KILME = sub { |
403 | die "received message on port without callback"; |
423 | (my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g; |
404 | } |
424 | kil $SELF, unhandled_message => "no callback found for message '$tag'"; |
|
|
425 | }; |
405 | |
426 | |
406 | sub port(;&) { |
427 | sub port(;&) { |
407 | my $id = $UNIQ . ++$ID; |
428 | my $id = $UNIQ . ++$ID; |
408 | my $port = "$NODE#$id"; |
429 | my $port = "$NODE#$id"; |
409 | |
430 | |
410 | rcv $port, shift || \&_kilme; |
431 | rcv $port, shift || $KILME; |
411 | |
432 | |
412 | $port |
433 | $port |
413 | } |
434 | } |
414 | |
435 | |
415 | =item rcv $local_port, $callback->(@msg) |
436 | =item rcv $local_port, $callback->(@msg) |
… | |
… | |
420 | |
441 | |
421 | The global C<$SELF> (exported by this module) contains C<$port> while |
442 | The global C<$SELF> (exported by this module) contains C<$port> while |
422 | executing the callback. Runtime errors during callback execution will |
443 | executing the callback. Runtime errors during callback execution will |
423 | result in the port being C<kil>ed. |
444 | result in the port being C<kil>ed. |
424 | |
445 | |
425 | The default callback received all messages not matched by a more specific |
446 | The default callback receives all messages not matched by a more specific |
426 | C<tag> match. |
447 | C<tag> match. |
427 | |
448 | |
428 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
449 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
429 | |
450 | |
430 | Register (or replace) callbacks to be called on messages starting with the |
451 | Register (or replace) callbacks to be called on messages starting with the |
… | |
… | |
465 | |
486 | |
466 | sub rcv($@) { |
487 | sub rcv($@) { |
467 | my $port = shift; |
488 | my $port = shift; |
468 | my ($nodeid, $portid) = split /#/, $port, 2; |
489 | my ($nodeid, $portid) = split /#/, $port, 2; |
469 | |
490 | |
470 | $NODE{$nodeid} == $NODE{""} |
491 | $nodeid eq $NODE |
471 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
492 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
472 | |
493 | |
473 | while (@_) { |
494 | while (@_) { |
474 | if (ref $_[0]) { |
495 | if (ref $_[0]) { |
475 | if (my $self = $PORT_DATA{$portid}) { |
496 | if (my $self = $PORT_DATA{$portid}) { |
… | |
… | |
518 | $port |
539 | $port |
519 | } |
540 | } |
520 | |
541 | |
521 | =item peval $port, $coderef[, @args] |
542 | =item peval $port, $coderef[, @args] |
522 | |
543 | |
523 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
544 | Evaluates the given C<$codref> within the context of C<$port>, that is, |
524 | when the code throews an exception the C<$port> will be killed. |
545 | when the code throws an exception the C<$port> will be killed. |
525 | |
546 | |
526 | Any remaining args will be passed to the callback. Any return values will |
547 | Any remaining args will be passed to the callback. Any return values will |
527 | be returned to the caller. |
548 | be returned to the caller. |
528 | |
549 | |
529 | This is useful when you temporarily want to execute code in the context of |
550 | This is useful when you temporarily want to execute code in the context of |
… | |
… | |
594 | $res |
615 | $res |
595 | } |
616 | } |
596 | } |
617 | } |
597 | } |
618 | } |
598 | |
619 | |
|
|
620 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
621 | |
|
|
622 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
623 | |
599 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
624 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
600 | |
|
|
601 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
602 | |
|
|
603 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
604 | |
625 | |
605 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
626 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
606 | |
627 | |
607 | Monitor the given port and do something when the port is killed or |
628 | Monitor the given port and do something when the port is killed or |
608 | messages to it were lost, and optionally return a guard that can be used |
629 | messages to it were lost, and optionally return a guard that can be used |
609 | to stop monitoring again. |
630 | to stop monitoring again. |
610 | |
631 | |
|
|
632 | The first two forms distinguish between "normal" and "abnormal" kil's: |
|
|
633 | |
|
|
634 | In the first form (another port given), if the C<$port> is C<kil>'ed with |
|
|
635 | a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the |
|
|
636 | same reason. That is, on "normal" kil's nothing happens, while under all |
|
|
637 | other conditions, the other port is killed with the same reason. |
|
|
638 | |
|
|
639 | The second form (kill self) is the same as the first form, except that |
|
|
640 | C<$rvport> defaults to C<$SELF>. |
|
|
641 | |
|
|
642 | The remaining forms don't distinguish between "normal" and "abnormal" kil's |
|
|
643 | - it's up to the callback or receiver to check whether the C<@reason> is |
|
|
644 | empty and act accordingly. |
|
|
645 | |
611 | In the first form (callback), the callback is simply called with any |
646 | In the third form (callback), the callback is simply called with any |
612 | number of C<@reason> elements (no @reason means that the port was deleted |
647 | number of C<@reason> elements (empty @reason means that the port was deleted |
613 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
648 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
614 | C<eval> if unsure. |
649 | C<eval> if unsure. |
615 | |
650 | |
616 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
617 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
618 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
619 | port is killed with the same reason. |
|
|
620 | |
|
|
621 | The third form (kill self) is the same as the second form, except that |
|
|
622 | C<$rvport> defaults to C<$SELF>. |
|
|
623 | |
|
|
624 | In the last form (message), a message of the form C<@msg, @reason> will be |
651 | In the last form (message), a message of the form C<$rcvport, @msg, |
625 | C<snd>. |
652 | @reason> will be C<snd>. |
626 | |
653 | |
627 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
654 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
628 | alert was raised), they are removed and will not trigger again. |
655 | alert was raised), they are removed and will not trigger again, even if it |
|
|
656 | turns out that the port is still alive. |
629 | |
657 | |
630 | As a rule of thumb, monitoring requests should always monitor a port from |
658 | As a rule of thumb, monitoring requests should always monitor a remote |
631 | a local port (or callback). The reason is that kill messages might get |
659 | port locally (using a local C<$rcvport> or a callback). The reason is that |
632 | lost, just like any other message. Another less obvious reason is that |
660 | kill messages might get lost, just like any other message. Another less |
633 | even monitoring requests can get lost (for example, when the connection |
661 | obvious reason is that even monitoring requests can get lost (for example, |
634 | to the other node goes down permanently). When monitoring a port locally |
662 | when the connection to the other node goes down permanently). When |
635 | these problems do not exist. |
663 | monitoring a port locally these problems do not exist. |
636 | |
664 | |
637 | C<mon> effectively guarantees that, in the absence of hardware failures, |
665 | C<mon> effectively guarantees that, in the absence of hardware failures, |
638 | after starting the monitor, either all messages sent to the port will |
666 | after starting the monitor, either all messages sent to the port will |
639 | arrive, or the monitoring action will be invoked after possible message |
667 | arrive, or the monitoring action will be invoked after possible message |
640 | loss has been detected. No messages will be lost "in between" (after |
668 | loss has been detected. No messages will be lost "in between" (after |
… | |
… | |
731 | will be reported as reason C<< die => $@ >>. |
759 | will be reported as reason C<< die => $@ >>. |
732 | |
760 | |
733 | Transport/communication errors are reported as C<< transport_error => |
761 | Transport/communication errors are reported as C<< transport_error => |
734 | $message >>. |
762 | $message >>. |
735 | |
763 | |
736 | =cut |
764 | Common idioms: |
|
|
765 | |
|
|
766 | # silently remove yourself, do not kill linked ports |
|
|
767 | kil $SELF; |
|
|
768 | |
|
|
769 | # report a failure in some detail |
|
|
770 | kil $SELF, failure_mode_1 => "it failed with too high temperature"; |
|
|
771 | |
|
|
772 | # do not waste much time with killing, just die when something goes wrong |
|
|
773 | open my $fh, "<file" |
|
|
774 | or die "file: $!"; |
737 | |
775 | |
738 | =item $port = spawn $node, $initfunc[, @initdata] |
776 | =item $port = spawn $node, $initfunc[, @initdata] |
739 | |
777 | |
740 | Creates a port on the node C<$node> (which can also be a port ID, in which |
778 | Creates a port on the node C<$node> (which can also be a port ID, in which |
741 | case it's the node where that port resides). |
779 | case it's the node where that port resides). |
… | |
… | |
833 | ref $action[0] |
871 | ref $action[0] |
834 | ? $action[0]() |
872 | ? $action[0]() |
835 | : snd @action; |
873 | : snd @action; |
836 | }; |
874 | }; |
837 | } |
875 | } |
|
|
876 | |
|
|
877 | #=item $cb2 = timeout $seconds, $cb[, @args] |
838 | |
878 | |
839 | =item cal $port, @msg, $callback[, $timeout] |
879 | =item cal $port, @msg, $callback[, $timeout] |
840 | |
880 | |
841 | A simple form of RPC - sends a message to the given C<$port> with the |
881 | A simple form of RPC - sends a message to the given C<$port> with the |
842 | given contents (C<@msg>), but adds a reply port to the message. |
882 | given contents (C<@msg>), but adds a reply port to the message. |
… | |
… | |
891 | =back |
931 | =back |
892 | |
932 | |
893 | =head1 DISTRIBUTED DATABASE |
933 | =head1 DISTRIBUTED DATABASE |
894 | |
934 | |
895 | AnyEvent::MP comes with a simple distributed database. The database will |
935 | AnyEvent::MP comes with a simple distributed database. The database will |
896 | be mirrored asynchronously at all global nodes. Other nodes bind to one of |
936 | be mirrored asynchronously on all global nodes. Other nodes bind to one |
897 | the global nodes for their needs. |
937 | of the global nodes for their needs. Every node has a "local database" |
|
|
938 | which contains all the values that are set locally. All local databases |
|
|
939 | are merged together to form the global database, which can be queried. |
898 | |
940 | |
899 | The database consists of a two-level hash - a hash contains a hash which |
941 | The database structure is that of a two-level hash - the database hash |
900 | contains values. |
942 | contains hashes which contain values, similarly to a perl hash of hashes, |
|
|
943 | i.e.: |
|
|
944 | |
|
|
945 | $DATABASE{$family}{$subkey} = $value |
901 | |
946 | |
902 | The top level hash key is called "family", and the second-level hash key |
947 | The top level hash key is called "family", and the second-level hash key |
903 | is called "subkey" or simply "key". |
948 | is called "subkey" or simply "key". |
904 | |
949 | |
905 | The family must be alphanumeric, i.e. start with a letter and consist |
950 | The family must be alphanumeric, i.e. start with a letter and consist |
… | |
… | |
910 | with the name of the application or module using it. |
955 | with the name of the application or module using it. |
911 | |
956 | |
912 | The subkeys must be non-empty strings, with no further restrictions. |
957 | The subkeys must be non-empty strings, with no further restrictions. |
913 | |
958 | |
914 | The values should preferably be strings, but other perl scalars should |
959 | The values should preferably be strings, but other perl scalars should |
915 | work as well (such as undef, arrays and hashes). |
960 | work as well (such as C<undef>, arrays and hashes). |
916 | |
961 | |
917 | Every database entry is owned by one node - adding the same family/subkey |
962 | Every database entry is owned by one node - adding the same family/subkey |
918 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
963 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
919 | but the result might be nondeterministic, i.e. the key might have |
964 | but the result might be nondeterministic, i.e. the key might have |
920 | different values on different nodes. |
965 | different values on different nodes. |
… | |
… | |
924 | pools. For example, a worker port for image scaling might do this: |
969 | pools. For example, a worker port for image scaling might do this: |
925 | |
970 | |
926 | db_set my_image_scalers => $port; |
971 | db_set my_image_scalers => $port; |
927 | |
972 | |
928 | And clients looking for an image scaler will want to get the |
973 | And clients looking for an image scaler will want to get the |
929 | C<my_image_scalers> keys: |
974 | C<my_image_scalers> keys from time to time: |
930 | |
975 | |
931 | db_keys "my_image_scalers" => 60 => sub { |
976 | db_keys my_image_scalers => sub { |
932 | #d##TODO# |
977 | @ports = @{ $_[0] }; |
|
|
978 | }; |
|
|
979 | |
|
|
980 | Or better yet, they want to monitor the database family, so they always |
|
|
981 | have a reasonable up-to-date copy: |
|
|
982 | |
|
|
983 | db_mon my_image_scalers => sub { |
|
|
984 | @ports = keys %{ $_[0] }; |
|
|
985 | }; |
|
|
986 | |
|
|
987 | In general, you can set or delete single subkeys, but query and monitor |
|
|
988 | whole families only. |
|
|
989 | |
|
|
990 | If you feel the need to monitor or query a single subkey, try giving it |
|
|
991 | it's own family. |
933 | |
992 | |
934 | =over |
993 | =over |
935 | |
994 | |
936 | =item db_set $family => $subkey [=> $value] |
995 | =item $guard = db_set $family => $subkey [=> $value] |
937 | |
996 | |
938 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
997 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
939 | C<undef> is used instead. |
998 | C<undef> is used instead. |
940 | |
999 | |
|
|
1000 | When called in non-void context, C<db_set> returns a guard that |
|
|
1001 | automatically calls C<db_del> when it is destroyed. |
|
|
1002 | |
941 | =item db_del $family => $subkey |
1003 | =item db_del $family => $subkey... |
942 | |
1004 | |
943 | Deletes a key from the database. |
1005 | Deletes one or more subkeys from the database family. |
944 | |
1006 | |
945 | =item $guard = db_reg $family => $subkey [=> $value] |
1007 | =item $guard = db_reg $family => $port => $value |
946 | |
1008 | |
947 | Sets the key on the database and returns a guard. When the guard is |
1009 | =item $guard = db_reg $family => $port |
948 | destroyed, the key is deleted from the database. If C<$value> is missing, |
1010 | |
949 | then C<undef> is used. |
1011 | =item $guard = db_reg $family |
|
|
1012 | |
|
|
1013 | Registers a port in the given family and optionally returns a guard to |
|
|
1014 | remove it. |
|
|
1015 | |
|
|
1016 | This function basically does the same as: |
|
|
1017 | |
|
|
1018 | db_set $family => $port => $value |
|
|
1019 | |
|
|
1020 | Except that the port is monitored and automatically removed from the |
|
|
1021 | database family when it is kil'ed. |
|
|
1022 | |
|
|
1023 | If C<$value> is missing, C<undef> is used. If C<$port> is missing, then |
|
|
1024 | C<$SELF> is used. |
|
|
1025 | |
|
|
1026 | This function is most useful to register a port in some port group (which |
|
|
1027 | is just another name for a database family), and have it removed when the |
|
|
1028 | port is gone. This works best when the port is a local port. |
|
|
1029 | |
|
|
1030 | =cut |
|
|
1031 | |
|
|
1032 | sub db_reg($$;$) { |
|
|
1033 | my $family = shift; |
|
|
1034 | my $port = @_ ? shift : $SELF; |
|
|
1035 | |
|
|
1036 | my $clr = sub { db_del $family => $port }; |
|
|
1037 | mon $port, $clr; |
|
|
1038 | |
|
|
1039 | db_set $family => $port => $_[0]; |
|
|
1040 | |
|
|
1041 | defined wantarray |
|
|
1042 | and &Guard::guard ($clr) |
|
|
1043 | } |
|
|
1044 | |
|
|
1045 | =item db_family $family => $cb->(\%familyhash) |
|
|
1046 | |
|
|
1047 | Queries the named database C<$family> and call the callback with the |
|
|
1048 | family represented as a hash. You can keep and freely modify the hash. |
|
|
1049 | |
|
|
1050 | =item db_keys $family => $cb->(\@keys) |
|
|
1051 | |
|
|
1052 | Same as C<db_family>, except it only queries the family I<subkeys> and passes |
|
|
1053 | them as array reference to the callback. |
|
|
1054 | |
|
|
1055 | =item db_values $family => $cb->(\@values) |
|
|
1056 | |
|
|
1057 | Same as C<db_family>, except it only queries the family I<values> and passes them |
|
|
1058 | as array reference to the callback. |
|
|
1059 | |
|
|
1060 | =item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted) |
|
|
1061 | |
|
|
1062 | Creates a monitor on the given database family. Each time a key is |
|
|
1063 | set or is deleted the callback is called with a hash containing the |
|
|
1064 | database family and three lists of added, changed and deleted subkeys, |
|
|
1065 | respectively. If no keys have changed then the array reference might be |
|
|
1066 | C<undef> or even missing. |
|
|
1067 | |
|
|
1068 | If not called in void context, a guard object is returned that, when |
|
|
1069 | destroyed, stops the monitor. |
|
|
1070 | |
|
|
1071 | The family hash reference and the key arrays belong to AnyEvent::MP and |
|
|
1072 | B<must not be modified or stored> by the callback. When in doubt, make a |
|
|
1073 | copy. |
|
|
1074 | |
|
|
1075 | As soon as possible after the monitoring starts, the callback will be |
|
|
1076 | called with the intiial contents of the family, even if it is empty, |
|
|
1077 | i.e. there will always be a timely call to the callback with the current |
|
|
1078 | contents. |
|
|
1079 | |
|
|
1080 | It is possible that the callback is called with a change event even though |
|
|
1081 | the subkey is already present and the value has not changed. |
|
|
1082 | |
|
|
1083 | The monitoring stops when the guard object is destroyed. |
|
|
1084 | |
|
|
1085 | Example: on every change to the family "mygroup", print out all keys. |
|
|
1086 | |
|
|
1087 | my $guard = db_mon mygroup => sub { |
|
|
1088 | my ($family, $a, $c, $d) = @_; |
|
|
1089 | print "mygroup members: ", (join " ", keys %$family), "\n"; |
|
|
1090 | }; |
|
|
1091 | |
|
|
1092 | Exmaple: wait until the family "My::Module::workers" is non-empty. |
|
|
1093 | |
|
|
1094 | my $guard; $guard = db_mon My::Module::workers => sub { |
|
|
1095 | my ($family, $a, $c, $d) = @_; |
|
|
1096 | return unless %$family; |
|
|
1097 | undef $guard; |
|
|
1098 | print "My::Module::workers now nonempty\n"; |
|
|
1099 | }; |
|
|
1100 | |
|
|
1101 | Example: print all changes to the family "AnyEvent::Fantasy::Module". |
|
|
1102 | |
|
|
1103 | my $guard = db_mon AnyEvent::Fantasy::Module => sub { |
|
|
1104 | my ($family, $a, $c, $d) = @_; |
|
|
1105 | |
|
|
1106 | print "+$_=$family->{$_}\n" for @$a; |
|
|
1107 | print "*$_=$family->{$_}\n" for @$c; |
|
|
1108 | print "-$_=$family->{$_}\n" for @$d; |
|
|
1109 | }; |
950 | |
1110 | |
951 | =cut |
1111 | =cut |
952 | |
1112 | |
953 | =back |
1113 | =back |
954 | |
1114 | |
… | |
… | |
999 | filter messages without dequeuing them. |
1159 | filter messages without dequeuing them. |
1000 | |
1160 | |
1001 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
1161 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
1002 | being event-based, while Erlang is process-based. |
1162 | being event-based, while Erlang is process-based. |
1003 | |
1163 | |
1004 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
1164 | You can have a look at L<Coro::MP> for a more Erlang-like process model on |
1005 | top of AEMP and Coro threads. |
1165 | top of AEMP and Coro threads. |
1006 | |
1166 | |
1007 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
1167 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
1008 | |
1168 | |
1009 | Sending messages in Erlang is synchronous and blocks the process until |
1169 | Sending messages in Erlang is synchronous and blocks the process until |
1010 | a conenction has been established and the message sent (and so does not |
1170 | a connection has been established and the message sent (and so does not |
1011 | need a queue that can overflow). AEMP sends return immediately, connection |
1171 | need a queue that can overflow). AEMP sends return immediately, connection |
1012 | establishment is handled in the background. |
1172 | establishment is handled in the background. |
1013 | |
1173 | |
1014 | =item * Erlang suffers from silent message loss, AEMP does not. |
1174 | =item * Erlang suffers from silent message loss, AEMP does not. |
1015 | |
1175 | |
… | |
… | |
1113 | Keeping your messages simple, concentrating on data structures rather than |
1273 | Keeping your messages simple, concentrating on data structures rather than |
1114 | objects, will keep your messages clean, tidy and efficient. |
1274 | objects, will keep your messages clean, tidy and efficient. |
1115 | |
1275 | |
1116 | =back |
1276 | =back |
1117 | |
1277 | |
|
|
1278 | =head1 PORTING FROM AnyEvent::MP VERSION 1.X |
|
|
1279 | |
|
|
1280 | AEMP version 2 has a few major incompatible changes compared to version 1: |
|
|
1281 | |
|
|
1282 | =over 4 |
|
|
1283 | |
|
|
1284 | =item AnyEvent::MP::Global no longer has group management functions. |
|
|
1285 | |
|
|
1286 | At least not officially - the grp_* functions are still exported and might |
|
|
1287 | work, but they will be removed in some later release. |
|
|
1288 | |
|
|
1289 | AnyEvent::MP now comes with a distributed database that is more |
|
|
1290 | powerful. Its database families map closely to port groups, but the API |
|
|
1291 | has changed (the functions are also now exported by AnyEvent::MP). Here is |
|
|
1292 | a rough porting guide: |
|
|
1293 | |
|
|
1294 | grp_reg $group, $port # old |
|
|
1295 | db_reg $group, $port # new |
|
|
1296 | |
|
|
1297 | $list = grp_get $group # old |
|
|
1298 | db_keys $group, sub { my $list = shift } # new |
|
|
1299 | |
|
|
1300 | grp_mon $group, $cb->(\@ports, $add, $del) # old |
|
|
1301 | db_mon $group, $cb->(\%ports, $add, $change, $del) # new |
|
|
1302 | |
|
|
1303 | C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is |
|
|
1304 | no longer instant, because the local node might not have a copy of the |
|
|
1305 | group. You can either modify your code to allow for a callback, or use |
|
|
1306 | C<db_mon> to keep an updated copy of the group: |
|
|
1307 | |
|
|
1308 | my $local_group_copy; |
|
|
1309 | db_mon $group => sub { $local_group_copy = $_[0] }; |
|
|
1310 | |
|
|
1311 | # now "keys %$local_group_copy" always returns the most up-to-date |
|
|
1312 | # list of ports in the group. |
|
|
1313 | |
|
|
1314 | C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon> |
|
|
1315 | passes a hash as first argument, and an extra C<$chg> argument that can be |
|
|
1316 | ignored: |
|
|
1317 | |
|
|
1318 | db_mon $group => sub { |
|
|
1319 | my ($ports, $add, $chg, $del) = @_; |
|
|
1320 | $ports = [keys %$ports]; |
|
|
1321 | |
|
|
1322 | # now $ports, $add and $del are the same as |
|
|
1323 | # were originally passed by grp_mon. |
|
|
1324 | ... |
|
|
1325 | }; |
|
|
1326 | |
|
|
1327 | =item Nodes not longer connect to all other nodes. |
|
|
1328 | |
|
|
1329 | In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global> |
|
|
1330 | module, which in turn would create connections to all other nodes in the |
|
|
1331 | network (helped by the seed nodes). |
|
|
1332 | |
|
|
1333 | In version 2.x, global nodes still connect to all other global nodes, but |
|
|
1334 | other nodes don't - now every node either is a global node itself, or |
|
|
1335 | attaches itself to another global node. |
|
|
1336 | |
|
|
1337 | If a node isn't a global node itself, then it attaches itself to one |
|
|
1338 | of its seed nodes. If that seed node isn't a global node yet, it will |
|
|
1339 | automatically be upgraded to a global node. |
|
|
1340 | |
|
|
1341 | So in many cases, nothing needs to be changed - one just has to make sure |
|
|
1342 | that all seed nodes are meshed together with the other seed nodes (as with |
|
|
1343 | AEMP 1.x), and other nodes specify them as seed nodes. This is most easily |
|
|
1344 | achieved by specifying the same set of seed nodes for all nodes in the |
|
|
1345 | network. |
|
|
1346 | |
|
|
1347 | Not opening a connection to every other node is usually an advantage, |
|
|
1348 | except when you need the lower latency of an already established |
|
|
1349 | connection. To ensure a node establishes a connection to another node, |
|
|
1350 | you can monitor the node port (C<mon $node, ...>), which will attempt to |
|
|
1351 | create the connection (and notify you when the connection fails). |
|
|
1352 | |
|
|
1353 | =item Listener-less nodes (nodes without binds) are gone. |
|
|
1354 | |
|
|
1355 | And are not coming back, at least not in their old form. If no C<binds> |
|
|
1356 | are specified for a node, AnyEvent::MP assumes a default of C<*:*>. |
|
|
1357 | |
|
|
1358 | There are vague plans to implement some form of routing domains, which |
|
|
1359 | might or might not bring back listener-less nodes, but don't count on it. |
|
|
1360 | |
|
|
1361 | The fact that most connections are now optional somewhat mitigates this, |
|
|
1362 | as a node can be effectively unreachable from the outside without any |
|
|
1363 | problems, as long as it isn't a global node and only reaches out to other |
|
|
1364 | nodes (as opposed to being contacted from other nodes). |
|
|
1365 | |
|
|
1366 | =item $AnyEvent::MP::Kernel::WARN has gone. |
|
|
1367 | |
|
|
1368 | AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now |
|
|
1369 | uses this, and so should your programs. |
|
|
1370 | |
|
|
1371 | Every module now documents what kinds of messages it generates, with |
|
|
1372 | AnyEvent::MP acting as a catch all. |
|
|
1373 | |
|
|
1374 | On the positive side, this means that instead of setting |
|
|
1375 | C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> - |
|
|
1376 | much less to type. |
|
|
1377 | |
|
|
1378 | =back |
|
|
1379 | |
|
|
1380 | =head1 LOGGING |
|
|
1381 | |
|
|
1382 | AnyEvent::MP does not normally log anything by itself, but since it is the |
|
|
1383 | root of the context hierarchy for AnyEvent::MP modules, it will receive |
|
|
1384 | all log messages by submodules. |
|
|
1385 | |
1118 | =head1 SEE ALSO |
1386 | =head1 SEE ALSO |
1119 | |
1387 | |
1120 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1388 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1121 | |
1389 | |
1122 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1390 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |