… | |
… | |
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 | |
|
|
52 | =head1 CURRENT STATUS |
|
|
53 | |
|
|
54 | bin/aemp - stable. |
|
|
55 | AnyEvent::MP - stable API, should work. |
|
|
56 | AnyEvent::MP::Intro - explains most concepts. |
|
|
57 | AnyEvent::MP::Kernel - mostly stable API. |
|
|
58 | AnyEvent::MP::Global - stable API. |
|
|
59 | |
51 | |
60 | =head1 DESCRIPTION |
52 | =head1 DESCRIPTION |
61 | |
53 | |
62 | This module (-family) implements a simple message passing framework. |
54 | This module (-family) implements a simple message passing framework. |
63 | |
55 | |
… | |
… | |
184 | |
176 | |
185 | use common::sense; |
177 | use common::sense; |
186 | |
178 | |
187 | use Carp (); |
179 | use Carp (); |
188 | |
180 | |
189 | use AE (); |
181 | use AnyEvent (); |
|
|
182 | use Guard (); |
190 | |
183 | |
191 | use base "Exporter"; |
184 | use base "Exporter"; |
192 | |
185 | |
193 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
186 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
194 | |
187 | |
195 | our @EXPORT = qw( |
188 | our @EXPORT = qw( |
196 | NODE $NODE *SELF node_of after |
189 | NODE $NODE *SELF node_of after |
197 | configure |
190 | configure |
198 | snd rcv mon mon_guard kil psub peval spawn cal |
191 | snd rcv mon mon_guard kil psub peval spawn cal |
199 | port |
192 | port |
|
|
193 | db_set db_del db_reg |
|
|
194 | db_mon db_family db_keys db_values |
200 | ); |
195 | ); |
201 | |
196 | |
202 | our $SELF; |
197 | our $SELF; |
203 | |
198 | |
204 | sub _self_die() { |
199 | sub _self_die() { |
… | |
… | |
228 | |
223 | |
229 | This function configures a node - it must be called exactly once (or |
224 | This function configures a node - it must be called exactly once (or |
230 | never) before calling other AnyEvent::MP functions. |
225 | never) before calling other AnyEvent::MP functions. |
231 | |
226 | |
232 | The key/value pairs are basically the same ones as documented for the |
227 | The key/value pairs are basically the same ones as documented for the |
233 | F<aemp> command line utility (sans the set/del prefix), with two additions: |
228 | F<aemp> command line utility (sans the set/del prefix), with these additions: |
234 | |
229 | |
235 | =over 4 |
230 | =over 4 |
236 | |
231 | |
237 | =item norc => $boolean (default false) |
232 | =item norc => $boolean (default false) |
238 | |
233 | |
… | |
… | |
243 | =item force => $boolean (default false) |
238 | =item force => $boolean (default false) |
244 | |
239 | |
245 | IF true, then the values specified in the C<configure> will take |
240 | IF true, then the values specified in the C<configure> will take |
246 | precedence over any values configured via the rc file. The default is for |
241 | precedence over any values configured via the rc file. The default is for |
247 | the rc file to override any options specified in the program. |
242 | the rc file to override any options specified in the program. |
|
|
243 | |
|
|
244 | =item secure => $pass->(@msg) |
|
|
245 | |
|
|
246 | In addition to specifying a boolean, you can specify a code reference that |
|
|
247 | is called for every code execution attempt - the execution request is |
|
|
248 | granted iff the callback returns a true value. |
|
|
249 | |
|
|
250 | Most of the time the callback should look only at |
|
|
251 | C<$AnyEvent::MP::Kernel::SRCNODE> to make a decision, and not at the |
|
|
252 | actual message (which can be about anything, and is mostly provided for |
|
|
253 | diagnostic purposes). |
|
|
254 | |
|
|
255 | See F<semp setsecure> for more info. |
248 | |
256 | |
249 | =back |
257 | =back |
250 | |
258 | |
251 | =over 4 |
259 | =over 4 |
252 | |
260 | |
… | |
… | |
269 | and the values specified directly via C<configure> have lowest priority, |
277 | and the values specified directly via C<configure> have lowest priority, |
270 | and can only be used to specify defaults. |
278 | and can only be used to specify defaults. |
271 | |
279 | |
272 | If the profile specifies a node ID, then this will become the node ID of |
280 | If the profile specifies a node ID, then this will become the node ID of |
273 | this process. If not, then the profile name will be used as node ID, with |
281 | this process. If not, then the profile name will be used as node ID, with |
274 | a slash (C</>) attached. |
282 | a unique randoms tring (C</%u>) appended. |
275 | |
283 | |
276 | If the node ID (or profile name) ends with a slash (C</>), then a random |
284 | The node ID can contain some C<%> sequences that are expanded: C<%n> |
277 | string is appended to make it unique. |
285 | is expanded to the local nodename, C<%u> is replaced by a random |
|
|
286 | strign to make the node unique. For example, the F<aemp> commandline |
|
|
287 | utility uses C<aemp/%n/%u> as nodename, which might expand to |
|
|
288 | C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>. |
278 | |
289 | |
279 | =item step 2, bind listener sockets |
290 | =item step 2, bind listener sockets |
280 | |
291 | |
281 | The next step is to look up the binds in the profile, followed by binding |
292 | The next step is to look up the binds in the profile, followed by binding |
282 | aemp protocol listeners on all binds specified (it is possible and valid |
293 | aemp protocol listeners on all binds specified (it is possible and valid |
… | |
… | |
299 | Example: become a distributed node using the local node name as profile. |
310 | Example: become a distributed node using the local node name as profile. |
300 | This should be the most common form of invocation for "daemon"-type nodes. |
311 | This should be the most common form of invocation for "daemon"-type nodes. |
301 | |
312 | |
302 | configure |
313 | configure |
303 | |
314 | |
304 | Example: become an anonymous node. This form is often used for commandline |
315 | Example: become a semi-anonymous node. This form is often used for |
305 | clients. |
316 | commandline clients. |
306 | |
317 | |
307 | configure nodeid => "anon/"; |
318 | configure nodeid => "myscript/%n/%u"; |
308 | |
319 | |
309 | Example: configure a node using a profile called seed, which is suitable |
320 | Example: configure a node using a profile called seed, which is suitable |
310 | for a seed node as it binds on all local addresses on a fixed port (4040, |
321 | for a seed node as it binds on all local addresses on a fixed port (4040, |
311 | customary for aemp). |
322 | customary for aemp). |
312 | |
323 | |
… | |
… | |
384 | |
395 | |
385 | =cut |
396 | =cut |
386 | |
397 | |
387 | sub rcv($@); |
398 | sub rcv($@); |
388 | |
399 | |
389 | sub _kilme { |
400 | my $KILME = sub { |
390 | die "received message on port without callback"; |
401 | (my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g; |
391 | } |
402 | kil $SELF, unhandled_message => "no callback found for message '$tag'"; |
|
|
403 | }; |
392 | |
404 | |
393 | sub port(;&) { |
405 | sub port(;&) { |
394 | my $id = $UNIQ . ++$ID; |
406 | my $id = $UNIQ . ++$ID; |
395 | my $port = "$NODE#$id"; |
407 | my $port = "$NODE#$id"; |
396 | |
408 | |
397 | rcv $port, shift || \&_kilme; |
409 | rcv $port, shift || $KILME; |
398 | |
410 | |
399 | $port |
411 | $port |
400 | } |
412 | } |
401 | |
413 | |
402 | =item rcv $local_port, $callback->(@msg) |
414 | =item rcv $local_port, $callback->(@msg) |
… | |
… | |
407 | |
419 | |
408 | The global C<$SELF> (exported by this module) contains C<$port> while |
420 | The global C<$SELF> (exported by this module) contains C<$port> while |
409 | executing the callback. Runtime errors during callback execution will |
421 | executing the callback. Runtime errors during callback execution will |
410 | result in the port being C<kil>ed. |
422 | result in the port being C<kil>ed. |
411 | |
423 | |
412 | The default callback received all messages not matched by a more specific |
424 | The default callback receives all messages not matched by a more specific |
413 | C<tag> match. |
425 | C<tag> match. |
414 | |
426 | |
415 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
427 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
416 | |
428 | |
417 | Register (or replace) callbacks to be called on messages starting with the |
429 | Register (or replace) callbacks to be called on messages starting with the |
… | |
… | |
581 | $res |
593 | $res |
582 | } |
594 | } |
583 | } |
595 | } |
584 | } |
596 | } |
585 | |
597 | |
|
|
598 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
599 | |
|
|
600 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
601 | |
586 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
602 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
587 | |
|
|
588 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
589 | |
|
|
590 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
591 | |
603 | |
592 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
604 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
593 | |
605 | |
594 | Monitor the given port and do something when the port is killed or |
606 | Monitor the given port and do something when the port is killed or |
595 | messages to it were lost, and optionally return a guard that can be used |
607 | messages to it were lost, and optionally return a guard that can be used |
596 | to stop monitoring again. |
608 | to stop monitoring again. |
597 | |
609 | |
|
|
610 | The first two forms distinguish between "normal" and "abnormal" kil's: |
|
|
611 | |
|
|
612 | In the first form (another port given), if the C<$port> is C<kil>'ed with |
|
|
613 | a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the |
|
|
614 | same reason. That is, on "normal" kil's nothing happens, while under all |
|
|
615 | other conditions, the other port is killed with the same reason. |
|
|
616 | |
|
|
617 | The second form (kill self) is the same as the first form, except that |
|
|
618 | C<$rvport> defaults to C<$SELF>. |
|
|
619 | |
|
|
620 | The remaining forms don't distinguish between "normal" and "abnormal" kil's |
|
|
621 | - it's up to the callback or receiver to check whether the C<@reason> is |
|
|
622 | empty and act accordingly. |
|
|
623 | |
598 | In the first form (callback), the callback is simply called with any |
624 | In the third form (callback), the callback is simply called with any |
599 | number of C<@reason> elements (no @reason means that the port was deleted |
625 | number of C<@reason> elements (empty @reason means that the port was deleted |
600 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
626 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
601 | C<eval> if unsure. |
627 | C<eval> if unsure. |
602 | |
628 | |
603 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
604 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
605 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
606 | port is killed with the same reason. |
|
|
607 | |
|
|
608 | The third form (kill self) is the same as the second form, except that |
|
|
609 | C<$rvport> defaults to C<$SELF>. |
|
|
610 | |
|
|
611 | In the last form (message), a message of the form C<@msg, @reason> will be |
629 | In the last form (message), a message of the form C<$rcvport, @msg, |
612 | C<snd>. |
630 | @reason> will be C<snd>. |
613 | |
631 | |
614 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
632 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
615 | alert was raised), they are removed and will not trigger again. |
633 | alert was raised), they are removed and will not trigger again, even if it |
|
|
634 | turns out that the port is still alive. |
616 | |
635 | |
617 | As a rule of thumb, monitoring requests should always monitor a port from |
636 | As a rule of thumb, monitoring requests should always monitor a remote |
618 | a local port (or callback). The reason is that kill messages might get |
637 | port locally (using a local C<$rcvport> or a callback). The reason is that |
619 | lost, just like any other message. Another less obvious reason is that |
638 | kill messages might get lost, just like any other message. Another less |
620 | even monitoring requests can get lost (for example, when the connection |
639 | obvious reason is that even monitoring requests can get lost (for example, |
621 | to the other node goes down permanently). When monitoring a port locally |
640 | when the connection to the other node goes down permanently). When |
622 | these problems do not exist. |
641 | monitoring a port locally these problems do not exist. |
623 | |
642 | |
624 | C<mon> effectively guarantees that, in the absence of hardware failures, |
643 | C<mon> effectively guarantees that, in the absence of hardware failures, |
625 | after starting the monitor, either all messages sent to the port will |
644 | after starting the monitor, either all messages sent to the port will |
626 | arrive, or the monitoring action will be invoked after possible message |
645 | arrive, or the monitoring action will be invoked after possible message |
627 | loss has been detected. No messages will be lost "in between" (after |
646 | loss has been detected. No messages will be lost "in between" (after |
… | |
… | |
672 | } |
691 | } |
673 | |
692 | |
674 | $node->monitor ($port, $cb); |
693 | $node->monitor ($port, $cb); |
675 | |
694 | |
676 | defined wantarray |
695 | defined wantarray |
677 | and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) |
696 | and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) }) |
678 | } |
697 | } |
679 | |
698 | |
680 | =item $guard = mon_guard $port, $ref, $ref... |
699 | =item $guard = mon_guard $port, $ref, $ref... |
681 | |
700 | |
682 | Monitors the given C<$port> and keeps the passed references. When the port |
701 | Monitors the given C<$port> and keeps the passed references. When the port |
… | |
… | |
718 | will be reported as reason C<< die => $@ >>. |
737 | will be reported as reason C<< die => $@ >>. |
719 | |
738 | |
720 | Transport/communication errors are reported as C<< transport_error => |
739 | Transport/communication errors are reported as C<< transport_error => |
721 | $message >>. |
740 | $message >>. |
722 | |
741 | |
723 | =cut |
742 | Common idioms: |
|
|
743 | |
|
|
744 | # silently remove yourself, do not kill linked ports |
|
|
745 | kil $SELF; |
|
|
746 | |
|
|
747 | # report a failure in some detail |
|
|
748 | kil $SELF, failure_mode_1 => "it failed with too high temperature"; |
|
|
749 | |
|
|
750 | # do not waste much time with killing, just die when something goes wrong |
|
|
751 | open my $fh, "<file" |
|
|
752 | or die "file: $!"; |
724 | |
753 | |
725 | =item $port = spawn $node, $initfunc[, @initdata] |
754 | =item $port = spawn $node, $initfunc[, @initdata] |
726 | |
755 | |
727 | Creates a port on the node C<$node> (which can also be a port ID, in which |
756 | Creates a port on the node C<$node> (which can also be a port ID, in which |
728 | case it's the node where that port resides). |
757 | case it's the node where that port resides). |
… | |
… | |
820 | ref $action[0] |
849 | ref $action[0] |
821 | ? $action[0]() |
850 | ? $action[0]() |
822 | : snd @action; |
851 | : snd @action; |
823 | }; |
852 | }; |
824 | } |
853 | } |
|
|
854 | |
|
|
855 | #=item $cb2 = timeout $seconds, $cb[, @args] |
825 | |
856 | |
826 | =item cal $port, @msg, $callback[, $timeout] |
857 | =item cal $port, @msg, $callback[, $timeout] |
827 | |
858 | |
828 | A simple form of RPC - sends a message to the given C<$port> with the |
859 | A simple form of RPC - sends a message to the given C<$port> with the |
829 | given contents (C<@msg>), but adds a reply port to the message. |
860 | given contents (C<@msg>), but adds a reply port to the message. |
… | |
… | |
875 | $port |
906 | $port |
876 | } |
907 | } |
877 | |
908 | |
878 | =back |
909 | =back |
879 | |
910 | |
|
|
911 | =head1 DISTRIBUTED DATABASE |
|
|
912 | |
|
|
913 | AnyEvent::MP comes with a simple distributed database. The database will |
|
|
914 | be mirrored asynchronously on all global nodes. Other nodes bind to one |
|
|
915 | of the global nodes for their needs. Every node has a "local database" |
|
|
916 | which contains all the values that are set locally. All local databases |
|
|
917 | are merged together to form the global database, which can be queried. |
|
|
918 | |
|
|
919 | The database structure is that of a two-level hash - the database hash |
|
|
920 | contains hashes which contain values, similarly to a perl hash of hashes, |
|
|
921 | i.e.: |
|
|
922 | |
|
|
923 | $DATABASE{$family}{$subkey} = $value |
|
|
924 | |
|
|
925 | The top level hash key is called "family", and the second-level hash key |
|
|
926 | is called "subkey" or simply "key". |
|
|
927 | |
|
|
928 | The family must be alphanumeric, i.e. start with a letter and consist |
|
|
929 | of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>, |
|
|
930 | pretty much like Perl module names. |
|
|
931 | |
|
|
932 | As the family namespace is global, it is recommended to prefix family names |
|
|
933 | with the name of the application or module using it. |
|
|
934 | |
|
|
935 | The subkeys must be non-empty strings, with no further restrictions. |
|
|
936 | |
|
|
937 | The values should preferably be strings, but other perl scalars should |
|
|
938 | work as well (such as C<undef>, arrays and hashes). |
|
|
939 | |
|
|
940 | Every database entry is owned by one node - adding the same family/subkey |
|
|
941 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
|
|
942 | but the result might be nondeterministic, i.e. the key might have |
|
|
943 | different values on different nodes. |
|
|
944 | |
|
|
945 | Different subkeys in the same family can be owned by different nodes |
|
|
946 | without problems, and in fact, this is the common method to create worker |
|
|
947 | pools. For example, a worker port for image scaling might do this: |
|
|
948 | |
|
|
949 | db_set my_image_scalers => $port; |
|
|
950 | |
|
|
951 | And clients looking for an image scaler will want to get the |
|
|
952 | C<my_image_scalers> keys from time to time: |
|
|
953 | |
|
|
954 | db_keys my_image_scalers => sub { |
|
|
955 | @ports = @{ $_[0] }; |
|
|
956 | }; |
|
|
957 | |
|
|
958 | Or better yet, they want to monitor the database family, so they always |
|
|
959 | have a reasonable up-to-date copy: |
|
|
960 | |
|
|
961 | db_mon my_image_scalers => sub { |
|
|
962 | @ports = keys %{ $_[0] }; |
|
|
963 | }; |
|
|
964 | |
|
|
965 | In general, you can set or delete single subkeys, but query and monitor |
|
|
966 | whole families only. |
|
|
967 | |
|
|
968 | If you feel the need to monitor or query a single subkey, try giving it |
|
|
969 | it's own family. |
|
|
970 | |
|
|
971 | =over |
|
|
972 | |
|
|
973 | =item $guard = db_set $family => $subkey [=> $value] |
|
|
974 | |
|
|
975 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
|
|
976 | C<undef> is used instead. |
|
|
977 | |
|
|
978 | When called in non-void context, C<db_set> returns a guard that |
|
|
979 | automatically calls C<db_del> when it is destroyed. |
|
|
980 | |
|
|
981 | =item db_del $family => $subkey... |
|
|
982 | |
|
|
983 | Deletes one or more subkeys from the database family. |
|
|
984 | |
|
|
985 | =item $guard = db_reg $family => $port => $value |
|
|
986 | |
|
|
987 | =item $guard = db_reg $family => $port |
|
|
988 | |
|
|
989 | =item $guard = db_reg $family |
|
|
990 | |
|
|
991 | Registers a port in the given family and optionally returns a guard to |
|
|
992 | remove it. |
|
|
993 | |
|
|
994 | This function basically does the same as: |
|
|
995 | |
|
|
996 | db_set $family => $port => $value |
|
|
997 | |
|
|
998 | Except that the port is monitored and automatically removed from the |
|
|
999 | database family when it is kil'ed. |
|
|
1000 | |
|
|
1001 | If C<$value> is missing, C<undef> is used. If C<$port> is missing, then |
|
|
1002 | C<$SELF> is used. |
|
|
1003 | |
|
|
1004 | This function is most useful to register a port in some port group (which |
|
|
1005 | is just another name for a database family), and have it removed when the |
|
|
1006 | port is gone. This works best when the port is a local port. |
|
|
1007 | |
|
|
1008 | =cut |
|
|
1009 | |
|
|
1010 | sub db_reg($$;$) { |
|
|
1011 | my $family = shift; |
|
|
1012 | my $port = @_ ? shift : $SELF; |
|
|
1013 | |
|
|
1014 | my $clr = sub { db_del $family => $port }; |
|
|
1015 | mon $port, $clr; |
|
|
1016 | |
|
|
1017 | db_set $family => $port => $_[0]; |
|
|
1018 | |
|
|
1019 | defined wantarray |
|
|
1020 | and &Guard::guard ($clr) |
|
|
1021 | } |
|
|
1022 | |
|
|
1023 | =item db_family $family => $cb->(\%familyhash) |
|
|
1024 | |
|
|
1025 | Queries the named database C<$family> and call the callback with the |
|
|
1026 | family represented as a hash. You can keep and freely modify the hash. |
|
|
1027 | |
|
|
1028 | =item db_keys $family => $cb->(\@keys) |
|
|
1029 | |
|
|
1030 | Same as C<db_family>, except it only queries the family I<subkeys> and passes |
|
|
1031 | them as array reference to the callback. |
|
|
1032 | |
|
|
1033 | =item db_values $family => $cb->(\@values) |
|
|
1034 | |
|
|
1035 | Same as C<db_family>, except it only queries the family I<values> and passes them |
|
|
1036 | as array reference to the callback. |
|
|
1037 | |
|
|
1038 | =item $guard = db_mon $family => $cb->($familyhash, \@added, \@changed, \@deleted) |
|
|
1039 | |
|
|
1040 | Creates a monitor on the given database family. Each time a key is set |
|
|
1041 | or or is deleted the callback is called with a hash containing the |
|
|
1042 | database family and three lists of added, changed and deleted subkeys, |
|
|
1043 | respectively. If no keys have changed then the array reference might be |
|
|
1044 | C<undef> or even missing. |
|
|
1045 | |
|
|
1046 | If not called in void context, a guard object is returned that, when |
|
|
1047 | destroyed, stops the monitor. |
|
|
1048 | |
|
|
1049 | The family hash reference and the key arrays belong to AnyEvent::MP and |
|
|
1050 | B<must not be modified or stored> by the callback. When in doubt, make a |
|
|
1051 | copy. |
|
|
1052 | |
|
|
1053 | As soon as possible after the monitoring starts, the callback will be |
|
|
1054 | called with the intiial contents of the family, even if it is empty, |
|
|
1055 | i.e. there will always be a timely call to the callback with the current |
|
|
1056 | contents. |
|
|
1057 | |
|
|
1058 | It is possible that the callback is called with a change event even though |
|
|
1059 | the subkey is already present and the value has not changed. |
|
|
1060 | |
|
|
1061 | The monitoring stops when the guard object is destroyed. |
|
|
1062 | |
|
|
1063 | Example: on every change to the family "mygroup", print out all keys. |
|
|
1064 | |
|
|
1065 | my $guard = db_mon mygroup => sub { |
|
|
1066 | my ($family, $a, $c, $d) = @_; |
|
|
1067 | print "mygroup members: ", (join " ", keys %$family), "\n"; |
|
|
1068 | }; |
|
|
1069 | |
|
|
1070 | Exmaple: wait until the family "My::Module::workers" is non-empty. |
|
|
1071 | |
|
|
1072 | my $guard; $guard = db_mon My::Module::workers => sub { |
|
|
1073 | my ($family, $a, $c, $d) = @_; |
|
|
1074 | return unless %$family; |
|
|
1075 | undef $guard; |
|
|
1076 | print "My::Module::workers now nonempty\n"; |
|
|
1077 | }; |
|
|
1078 | |
|
|
1079 | Example: print all changes to the family "AnyRvent::Fantasy::Module". |
|
|
1080 | |
|
|
1081 | my $guard = db_mon AnyRvent::Fantasy::Module => sub { |
|
|
1082 | my ($family, $a, $c, $d) = @_; |
|
|
1083 | |
|
|
1084 | print "+$_=$family->{$_}\n" for @$a; |
|
|
1085 | print "*$_=$family->{$_}\n" for @$c; |
|
|
1086 | print "-$_=$family->{$_}\n" for @$d; |
|
|
1087 | }; |
|
|
1088 | |
|
|
1089 | =cut |
|
|
1090 | |
|
|
1091 | =back |
|
|
1092 | |
880 | =head1 AnyEvent::MP vs. Distributed Erlang |
1093 | =head1 AnyEvent::MP vs. Distributed Erlang |
881 | |
1094 | |
882 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
1095 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
883 | == aemp node, Erlang process == aemp port), so many of the documents and |
1096 | == aemp node, Erlang process == aemp port), so many of the documents and |
884 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
1097 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
… | |
… | |
1038 | Keeping your messages simple, concentrating on data structures rather than |
1251 | Keeping your messages simple, concentrating on data structures rather than |
1039 | objects, will keep your messages clean, tidy and efficient. |
1252 | objects, will keep your messages clean, tidy and efficient. |
1040 | |
1253 | |
1041 | =back |
1254 | =back |
1042 | |
1255 | |
|
|
1256 | =head1 PORTING FROM AnyEvent::MP VERSION 1.X |
|
|
1257 | |
|
|
1258 | AEMP version 2 has a few major incompatible changes compared to version 1: |
|
|
1259 | |
|
|
1260 | =over 4 |
|
|
1261 | |
|
|
1262 | =item AnyEvent::MP::Global no longer has group management functions. |
|
|
1263 | |
|
|
1264 | At least not officially - the grp_* functions are still exported and might |
|
|
1265 | work, but they will be removed in some later release. |
|
|
1266 | |
|
|
1267 | AnyEvent::MP now comes with a distributed database that is more |
|
|
1268 | powerful. Its database families map closely to port groups, but the API |
|
|
1269 | has changed (the functions are also now exported by AnyEvent::MP). Here is |
|
|
1270 | a rough porting guide: |
|
|
1271 | |
|
|
1272 | grp_reg $group, $port # old |
|
|
1273 | db_reg $group, $port # new |
|
|
1274 | |
|
|
1275 | $list = grp_get $group # old |
|
|
1276 | db_keys $group, sub { my $list = shift } # new |
|
|
1277 | |
|
|
1278 | grp_mon $group, $cb->(\@ports, $add, $del) # old |
|
|
1279 | db_mon $group, $cb->(\%ports, $add, $change, $del) # new |
|
|
1280 | |
|
|
1281 | C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is |
|
|
1282 | no longer instant, because the local node might not have a copy of the |
|
|
1283 | group. You can either modify your code to allow for a callback, or use |
|
|
1284 | C<db_mon> to keep an updated copy of the group: |
|
|
1285 | |
|
|
1286 | my $local_group_copy; |
|
|
1287 | db_mon $group => sub { $local_group_copy = $_[0] }; |
|
|
1288 | |
|
|
1289 | # now "keys %$local_group_copy" always returns the most up-to-date |
|
|
1290 | # list of ports in the group. |
|
|
1291 | |
|
|
1292 | C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon> |
|
|
1293 | passes a hash as first argument, and an extra C<$chg> argument that can be |
|
|
1294 | ignored: |
|
|
1295 | |
|
|
1296 | db_mon $group => sub { |
|
|
1297 | my ($ports, $add, $chg, $lde) = @_; |
|
|
1298 | $ports = [keys %$ports]; |
|
|
1299 | |
|
|
1300 | # now $ports, $add and $del are the same as |
|
|
1301 | # were originally passed by grp_mon. |
|
|
1302 | ... |
|
|
1303 | }; |
|
|
1304 | |
|
|
1305 | =item Nodes not longer connect to all other nodes. |
|
|
1306 | |
|
|
1307 | In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global> |
|
|
1308 | module, which in turn would create connections to all other nodes in the |
|
|
1309 | network (helped by the seed nodes). |
|
|
1310 | |
|
|
1311 | In version 2.x, global nodes still connect to all other global nodes, but |
|
|
1312 | other nodes don't - now every node either is a global node itself, or |
|
|
1313 | attaches itself to another global node. |
|
|
1314 | |
|
|
1315 | If a node isn't a global node itself, then it attaches itself to one |
|
|
1316 | of its seed nodes. If that seed node isn't a global node yet, it will |
|
|
1317 | automatically be upgraded to a global node. |
|
|
1318 | |
|
|
1319 | So in many cases, nothing needs to be changed - one just has to make sure |
|
|
1320 | that all seed nodes are meshed together with the other seed nodes (as with |
|
|
1321 | AEMP 1.x), and other nodes specify them as seed nodes. This is most easily |
|
|
1322 | achieved by specifying the same set of seed nodes for all nodes in the |
|
|
1323 | network. |
|
|
1324 | |
|
|
1325 | Not opening a connection to every other node is usually an advantage, |
|
|
1326 | except when you need the lower latency of an already established |
|
|
1327 | connection. To ensure a node establishes a connection to another node, |
|
|
1328 | you can monitor the node port (C<mon $node, ...>), which will attempt to |
|
|
1329 | create the connection (and notify you when the connection fails). |
|
|
1330 | |
|
|
1331 | =item Listener-less nodes (nodes without binds) are gone. |
|
|
1332 | |
|
|
1333 | And are not coming back, at least not in their old form. If no C<binds> |
|
|
1334 | are specified for a node, AnyEvent::MP assumes a default of C<*:*>. |
|
|
1335 | |
|
|
1336 | There are vague plans to implement some form of routing domains, which |
|
|
1337 | might or might not bring back listener-less nodes, but don't count on it. |
|
|
1338 | |
|
|
1339 | The fact that most connections are now optional somewhat mitigates this, |
|
|
1340 | as a node can be effectively unreachable from the outside without any |
|
|
1341 | problems, as long as it isn't a global node and only reaches out to other |
|
|
1342 | nodes (as opposed to being contacted from other nodes). |
|
|
1343 | |
|
|
1344 | =item $AnyEvent::MP::Kernel::WARN has gone. |
|
|
1345 | |
|
|
1346 | AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now |
|
|
1347 | uses this, and so should your programs. |
|
|
1348 | |
|
|
1349 | Every module now documents what kinds of messages it generates, with |
|
|
1350 | AnyEvent::MP acting as a catch all. |
|
|
1351 | |
|
|
1352 | On the positive side, this means that instead of setting |
|
|
1353 | C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> - |
|
|
1354 | much less to type. |
|
|
1355 | |
|
|
1356 | =back |
|
|
1357 | |
|
|
1358 | =head1 LOGGING |
|
|
1359 | |
|
|
1360 | AnyEvent::MP does not normally log anything by itself, but sinc eit is the |
|
|
1361 | root of the contetx hierarchy for AnyEvent::MP modules, it will receive |
|
|
1362 | all log messages by submodules. |
|
|
1363 | |
1043 | =head1 SEE ALSO |
1364 | =head1 SEE ALSO |
1044 | |
1365 | |
1045 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1366 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1046 | |
1367 | |
1047 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1368 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |