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Revision 1.155 by root, Sat Sep 18 13:46:56 2021 UTC

118each other. To do this, nodes should listen on one or more local transport 118each other. To do this, nodes should listen on one or more local transport
119endpoints - binds. 119endpoints - binds.
120 120
121Currently, only standard C<ip:port> specifications can be used, which 121Currently, only standard C<ip:port> specifications can be used, which
122specify TCP ports to listen on. So a bind is basically just a tcp socket 122specify TCP ports to listen on. So a bind is basically just a tcp socket
123in listening mode thta accepts conenctions form other nodes. 123in listening mode that accepts connections from other nodes.
124 124
125=item seed nodes 125=item seed nodes
126 126
127When a node starts, it knows nothing about the network it is in - it 127When a node starts, it knows nothing about the network it is in - it
128needs to connect to at least one other node that is already in the 128needs to connect to at least one other node that is already in the
129network. These other nodes are called "seed nodes". 129network. These other nodes are called "seed nodes".
130 130
131Seed nodes themselves are not special - they are seed nodes only because 131Seed nodes themselves are not special - they are seed nodes only because
132some other node I<uses> them as such, but any node can be used as seed 132some other node I<uses> them as such, but any node can be used as seed
133node for other nodes, and eahc node cna use a different set of seed nodes. 133node for other nodes, and eahc node can use a different set of seed nodes.
134 134
135In addition to discovering the network, seed nodes are also used to 135In addition to discovering the network, seed nodes are also used to
136maintain the network - all nodes using the same seed node form are part of 136maintain the network - all nodes using the same seed node are part of the
137the same network. If a network is split into multiple subnets because e.g. 137same network. If a network is split into multiple subnets because e.g. the
138the network link between the parts goes down, then using the same seed 138network link between the parts goes down, then using the same seed nodes
139nodes for all nodes ensures that eventually the subnets get merged again. 139for all nodes ensures that eventually the subnets get merged again.
140 140
141Seed nodes are expected to be long-running, and at least one seed node 141Seed nodes are expected to be long-running, and at least one seed node
142should always be available. They should also be relatively responsive - a 142should always be available. They should also be relatively responsive - a
143seed node that blocks for long periods will slow down everybody else. 143seed node that blocks for long periods will slow down everybody else.
144 144
168 168
169Any node that loads the L<AnyEvent::MP::Global> module becomes a global 169Any node that loads the L<AnyEvent::MP::Global> module becomes a global
170node and tries to keep connections to all other nodes. So while it can 170node and tries to keep connections to all other nodes. So while it can
171make sense to make every node "global" in small networks, it usually makes 171make sense to make every node "global" in small networks, it usually makes
172sense to only make seed nodes into global nodes in large networks (nodes 172sense to only make seed nodes into global nodes in large networks (nodes
173keep connections to seed nodes and global nodes, so makign them the same 173keep connections to seed nodes and global nodes, so making them the same
174reduces overhead). 174reduces overhead).
175 175
176=back 176=back
177 177
178=head1 VARIABLES/FUNCTIONS 178=head1 VARIABLES/FUNCTIONS
204use AnyEvent (); 204use AnyEvent ();
205use Guard (); 205use Guard ();
206 206
207use base "Exporter"; 207use base "Exporter";
208 208
209our $VERSION = $AnyEvent::MP::Config::VERSION; 209our $VERSION = '2.02'; # also in MP/Config.pm
210 210
211our @EXPORT = qw( 211our @EXPORT = qw(
212 configure
213
212 NODE $NODE 214 NODE $NODE
213 configure 215 *SELF
216
214 node_of port_is_local 217 node_of port_is_local
218
215 snd kil 219 snd kil
216 db_set db_del
217 db_mon db_family db_keys db_values
218
219 *SELF
220
221 port rcv mon mon_guard psub peval spawn cal 220 port rcv mon mon_guard psub peval spawn cal
222 db_set db_del db_reg 221 db_set db_del db_reg
223 db_mon db_family db_keys db_values 222 db_mon db_family db_keys db_values
224 223
225 after 224 after
303this process. If not, then the profile name will be used as node ID, with 302this process. If not, then the profile name will be used as node ID, with
304a unique randoms tring (C</%u>) appended. 303a unique randoms tring (C</%u>) appended.
305 304
306The node ID can contain some C<%> sequences that are expanded: C<%n> 305The node ID can contain some C<%> sequences that are expanded: C<%n>
307is expanded to the local nodename, C<%u> is replaced by a random 306is expanded to the local nodename, C<%u> is replaced by a random
308strign to make the node unique. For example, the F<aemp> commandline 307string to make the node unique. For example, the F<aemp> commandline
309utility uses C<aemp/%n/%u> as nodename, which might expand to 308utility uses C<aemp/%n/%u> as nodename, which might expand to
310C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>. 309C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>.
311 310
312=item step 2, bind listener sockets 311=item step 2, bind listener sockets
313 312
314The next step is to look up the binds in the profile, followed by binding 313The next step is to look up the binds in the profile, followed by binding
315aemp protocol listeners on all binds specified (it is possible and valid 314aemp protocol listeners on all binds specified (it is possible and valid
316to have no binds, meaning that the node cannot be contacted form the 315to have no binds, meaning that the node cannot be contacted from the
317outside. This means the node cannot talk to other nodes that also have no 316outside. This means the node cannot talk to other nodes that also have no
318binds, but it can still talk to all "normal" nodes). 317binds, but it can still talk to all "normal" nodes).
319 318
320If the profile does not specify a binds list, then a default of C<*> is 319If the profile does not specify a binds list, then a default of C<*> is
321used, meaning the node will bind on a dynamically-assigned port on every 320used, meaning the node will bind on a dynamically-assigned port on every
418=cut 417=cut
419 418
420sub rcv($@); 419sub rcv($@);
421 420
422my $KILME = sub { 421my $KILME = sub {
423 (my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g; 422 (my $tag = substr $_[0], 0, 30) =~ s/([^\x20-\x7e])/./g;
424 kil $SELF, unhandled_message => "no callback found for message '$tag'"; 423 kil $SELF, unhandled_message => "no callback found for message '$tag'";
425}; 424};
426 425
427sub port(;&) { 426sub port(;&) {
428 my $id = $UNIQ . ++$ID; 427 my $id = $UNIQ . ++$ID;
539 $port 538 $port
540} 539}
541 540
542=item peval $port, $coderef[, @args] 541=item peval $port, $coderef[, @args]
543 542
544Evaluates the given C<$codref> within the contetx of C<$port>, that is, 543Evaluates the given C<$codref> within the context of C<$port>, that is,
545when the code throws an exception the C<$port> will be killed. 544when the code throws an exception the C<$port> will be killed.
546 545
547Any remaining args will be passed to the callback. Any return values will 546Any remaining args will be passed to the callback. Any return values will
548be returned to the caller. 547be returned to the caller.
549 548
651In the last form (message), a message of the form C<$rcvport, @msg, 650In the last form (message), a message of the form C<$rcvport, @msg,
652@reason> will be C<snd>. 651@reason> will be C<snd>.
653 652
654Monitoring-actions are one-shot: once messages are lost (and a monitoring 653Monitoring-actions are one-shot: once messages are lost (and a monitoring
655alert was raised), they are removed and will not trigger again, even if it 654alert was raised), they are removed and will not trigger again, even if it
656turns out that the port is still alive. 655turns out that the port is still alive (but monitoring actions added after
656that will again trigger).
657 657
658As a rule of thumb, monitoring requests should always monitor a remote 658As a rule of thumb, monitoring requests should always monitor a remote
659port locally (using a local C<$rcvport> or a callback). The reason is that 659port locally (using a local C<$rcvport> or a callback). The reason is that
660kill messages might get lost, just like any other message. Another less 660kill messages might get lost, just like any other message. Another less
661obvious reason is that even monitoring requests can get lost (for example, 661obvious reason is that even monitoring requests can get lost (for example,
877#=item $cb2 = timeout $seconds, $cb[, @args] 877#=item $cb2 = timeout $seconds, $cb[, @args]
878 878
879=item cal $port, @msg, $callback[, $timeout] 879=item cal $port, @msg, $callback[, $timeout]
880 880
881A simple form of RPC - sends a message to the given C<$port> with the 881A simple form of RPC - sends a message to the given C<$port> with the
882given contents (C<@msg>), but adds a reply port to the message. 882given contents (C<@msg>), but appends a reply port to the message.
883 883
884The reply port is created temporarily just for the purpose of receiving 884The reply port is created temporarily just for the purpose of receiving
885the reply, and will be C<kil>ed when no longer needed. 885the reply, and will be C<kil>ed when no longer needed.
886 886
887A reply message sent to the port is passed to the C<$callback> as-is. 887A reply message sent to the port is passed to the C<$callback> as-is.
1057Same as C<db_family>, except it only queries the family I<values> and passes them 1057Same as C<db_family>, except it only queries the family I<values> and passes them
1058as array reference to the callback. 1058as array reference to the callback.
1059 1059
1060=item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted) 1060=item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted)
1061 1061
1062Creates a monitor on the given database family. Each time a key is set 1062Creates a monitor on the given database family. Each time a key is
1063or or is deleted the callback is called with a hash containing the 1063set or is deleted the callback is called with a hash containing the
1064database family and three lists of added, changed and deleted subkeys, 1064database family and three lists of added, changed and deleted subkeys,
1065respectively. If no keys have changed then the array reference might be 1065respectively. If no keys have changed then the array reference might be
1066C<undef> or even missing. 1066C<undef> or even missing.
1067 1067
1068If not called in void context, a guard object is returned that, when 1068If not called in void context, a guard object is returned that, when
1096 return unless %$family; 1096 return unless %$family;
1097 undef $guard; 1097 undef $guard;
1098 print "My::Module::workers now nonempty\n"; 1098 print "My::Module::workers now nonempty\n";
1099 }; 1099 };
1100 1100
1101Example: print all changes to the family "AnyRvent::Fantasy::Module". 1101Example: print all changes to the family "AnyEvent::Fantasy::Module".
1102 1102
1103 my $guard = db_mon AnyRvent::Fantasy::Module => sub { 1103 my $guard = db_mon AnyEvent::Fantasy::Module => sub {
1104 my ($family, $a, $c, $d) = @_; 1104 my ($family, $a, $c, $d) = @_;
1105 1105
1106 print "+$_=$family->{$_}\n" for @$a; 1106 print "+$_=$family->{$_}\n" for @$a;
1107 print "*$_=$family->{$_}\n" for @$c; 1107 print "*$_=$family->{$_}\n" for @$c;
1108 print "-$_=$family->{$_}\n" for @$d; 1108 print "-$_=$family->{$_}\n" for @$d;
1159filter messages without dequeuing them. 1159filter messages without dequeuing them.
1160 1160
1161This is not a philosophical difference, but simply stems from AnyEvent::MP 1161This is not a philosophical difference, but simply stems from AnyEvent::MP
1162being event-based, while Erlang is process-based. 1162being event-based, while Erlang is process-based.
1163 1163
1164You cna have a look at L<Coro::MP> for a more Erlang-like process model on 1164You can have a look at L<Coro::MP> for a more Erlang-like process model on
1165top of AEMP and Coro threads. 1165top of AEMP and Coro threads.
1166 1166
1167=item * Erlang sends are synchronous, AEMP sends are asynchronous. 1167=item * Erlang sends are synchronous, AEMP sends are asynchronous.
1168 1168
1169Sending messages in Erlang is synchronous and blocks the process until 1169Sending messages in Erlang is synchronous and blocks the process until
1170a conenction has been established and the message sent (and so does not 1170a connection has been established and the message sent (and so does not
1171need a queue that can overflow). AEMP sends return immediately, connection 1171need a queue that can overflow). AEMP sends return immediately, connection
1172establishment is handled in the background. 1172establishment is handled in the background.
1173 1173
1174=item * Erlang suffers from silent message loss, AEMP does not. 1174=item * Erlang suffers from silent message loss, AEMP does not.
1175 1175
1314C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon> 1314C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon>
1315passes a hash as first argument, and an extra C<$chg> argument that can be 1315passes a hash as first argument, and an extra C<$chg> argument that can be
1316ignored: 1316ignored:
1317 1317
1318 db_mon $group => sub { 1318 db_mon $group => sub {
1319 my ($ports, $add, $chg, $lde) = @_; 1319 my ($ports, $add, $chg, $del) = @_;
1320 $ports = [keys %$ports]; 1320 $ports = [keys %$ports];
1321 1321
1322 # now $ports, $add and $del are the same as 1322 # now $ports, $add and $del are the same as
1323 # were originally passed by grp_mon. 1323 # were originally passed by grp_mon.
1324 ... 1324 ...
1377 1377
1378=back 1378=back
1379 1379
1380=head1 LOGGING 1380=head1 LOGGING
1381 1381
1382AnyEvent::MP does not normally log anything by itself, but sinc eit is the 1382AnyEvent::MP does not normally log anything by itself, but since it is the
1383root of the contetx hierarchy for AnyEvent::MP modules, it will receive 1383root of the context hierarchy for AnyEvent::MP modules, it will receive
1384all log messages by submodules. 1384all log messages by submodules.
1385 1385
1386=head1 SEE ALSO 1386=head1 SEE ALSO
1387 1387
1388L<AnyEvent::MP::Intro> - a gentle introduction. 1388L<AnyEvent::MP::Intro> - a gentle introduction.

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