--- AnyEvent-MP/MP.pm 2009/08/04 23:16:57 1.29 +++ AnyEvent-MP/MP.pm 2009/12/30 15:49:05 1.109 @@ -1,43 +1,71 @@ =head1 NAME -AnyEvent::MP - multi-processing/message-passing framework +AnyEvent::MP - erlang-style multi-processing/message-passing framework =head1 SYNOPSIS use AnyEvent::MP; - $NODE # contains this node's noderef - NODE # returns this node's noderef - NODE $port # returns the noderef of the port + $NODE # contains this node's node ID + NODE # returns this node's node ID + $SELF # receiving/own port id in rcv callbacks + + # initialise the node so it can send/receive messages + configure; + + # ports are message destinations + + # sending messages snd $port, type => data...; + snd $port, @msg; + snd @msg_with_first_element_being_a_port; - $SELF # receiving/own port id in rcv callbacks + # creating/using ports, the simple way + my $simple_port = port { my @msg = @_ }; - rcv $port, smartmatch => $cb->($port, @msg); + # creating/using ports, tagged message matching + my $port = port; + rcv $port, ping => sub { snd $_[0], "pong" }; + rcv $port, pong => sub { warn "pong received\n" }; + + # create a port on another node + my $port = spawn $node, $initfunc, @initdata; + + # destroy a prot again + kil $port; # "normal" kill + kil $port, my_error => "everything is broken"; # error kill + + # monitoring + mon $localport, $cb->(@msg) # callback is invoked on death + mon $localport, $otherport # kill otherport on abnormal death + mon $localport, $otherport, @msg # send message on death + + # temporarily execute code in port context + peval $port, sub { die "kill the port!" }; + + # execute callbacks in $SELF port context + my $timer = AE::timer 1, 0, psub { + die "kill the port, delayed"; + }; + +=head1 CURRENT STATUS - # examples: - rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; - rcv $port1, pong => sub { warn "pong received\n" }; - snd $port2, ping => $port1; - - # more, smarter, matches (_any_ is exported by this module) - rcv $port, [child_died => $pid] => sub { ... - rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 + bin/aemp - stable. + AnyEvent::MP - stable API, should work. + AnyEvent::MP::Intro - explains most concepts. + AnyEvent::MP::Kernel - mostly stable API. + AnyEvent::MP::Global - stable API. =head1 DESCRIPTION This module (-family) implements a simple message passing framework. Despite its simplicity, you can securely message other processes running -on the same or other hosts. +on the same or other hosts, and you can supervise entities remotely. For an introduction to this module family, see the L -manual page. - -At the moment, this module family is severly broken and underdocumented, -so do not use. This was uploaded mainly to reserve the CPAN namespace - -stay tuned! The basic API should be finished, however. +manual page and the examples under F. =head1 CONCEPTS @@ -45,42 +73,69 @@ =item port -A port is something you can send messages to (with the C function). +Not to be confused with a TCP port, a "port" is something you can send +messages to (with the C function). + +Ports allow you to register C handlers that can match all or just +some messages. Messages send to ports will not be queued, regardless of +anything was listening for them or not. -Some ports allow you to register C handlers that can match specific -messages. All C handlers will receive messages they match, messages -will not be queued. - -=item port id - C - -A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as -separator, and a port name (a printable string of unspecified format). An -exception is the the node port, whose ID is identical to it's node -reference. +=item port ID - C + +A port ID is the concatenation of a node ID, a hash-mark (C<#>) as +separator, and a port name (a printable string of unspecified format). =item node -A node is a single process containing at least one port - the node -port. You can send messages to node ports to find existing ports or to -create new ports, among other things. +A node is a single process containing at least one port - the node port, +which enables nodes to manage each other remotely, and to create new +ports. + +Nodes are either public (have one or more listening ports) or private +(no listening ports). Private nodes cannot talk to other private nodes +currently. + +=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*> + +A node ID is a string that uniquely identifies the node within a +network. Depending on the configuration used, node IDs can look like a +hostname, a hostname and a port, or a random string. AnyEvent::MP itself +doesn't interpret node IDs in any way. + +=item binds - C + +Nodes can only talk to each other by creating some kind of connection to +each other. To do this, nodes should listen on one or more local transport +endpoints - binds. Currently, only standard C specifications can +be used, which specify TCP ports to listen on. + +=item seed nodes + +When a node starts, it knows nothing about the network. To teach the node +about the network it first has to contact some other node within the +network. This node is called a seed. -Nodes are either private (single-process only), slaves (connected to a -master node only) or public nodes (connectable from unrelated nodes). +Apart from the fact that other nodes know them as seed nodes and they have +to have fixed listening addresses, seed nodes are perfectly normal nodes - +any node can function as a seed node for others. -=item noderef - C, C, C +In addition to discovering the network, seed nodes are also used to +maintain the network and to connect nodes that otherwise would have +trouble connecting. They form the backbone of an AnyEvent::MP network. -A node reference is a string that either simply identifies the node (for -private and slave nodes), or contains a recipe on how to reach a given -node (for public nodes). +Seed nodes are expected to be long-running, and at least one seed node +should always be available. They should also be relatively responsive - a +seed node that blocks for long periods will slow down everybody else. -This recipe is simply a comma-separated list of C pairs (for -TCP/IP, other protocols might look different). +=item seeds - C -Node references come in two flavours: resolved (containing only numerical -addresses) or unresolved (where hostnames are used instead of addresses). +Seeds are transport endpoint(s) (usually a hostname/IP address and a +TCP port) of nodes that should be used as seed nodes. -Before using an unresolved node reference in a message you first have to -resolve it. +The nodes listening on those endpoints are expected to be long-running, +and at least one of those should always be available. When nodes run out +of connections (e.g. due to a network error), they try to re-establish +connections to some seednodes again to join the network. =back @@ -92,7 +147,7 @@ package AnyEvent::MP; -use AnyEvent::MP::Base; +use AnyEvent::MP::Kernel; use common::sense; @@ -102,12 +157,12 @@ use base "Exporter"; -our $VERSION = '0.1'; +our $VERSION = 1.26; + our @EXPORT = qw( - NODE $NODE *SELF node_of _any_ - resolve_node - become_slave become_public - snd rcv mon kil reg psub + NODE $NODE *SELF node_of after + configure + snd rcv mon mon_guard kil psub peval spawn cal port ); @@ -121,329 +176,317 @@ =item $thisnode = NODE / $NODE -The C function returns, and the C<$NODE> variable contains -the noderef of the local node. The value is initialised by a call -to C or C, after which all local port -identifiers become invalid. +The C function returns, and the C<$NODE> variable contains, the node +ID of the node running in the current process. This value is initialised by +a call to C. + +=item $nodeid = node_of $port -=item $noderef = node_of $portid +Extracts and returns the node ID from a port ID or a node ID. -Extracts and returns the noderef from a portid or a noderef. +=item configure $profile, key => value... -=item $cv = resolve_node $noderef +=item configure key => value... -Takes an unresolved node reference that may contain hostnames and -abbreviated IDs, resolves all of them and returns a resolved node -reference. +Before a node can talk to other nodes on the network (i.e. enter +"distributed mode") it has to configure itself - the minimum a node needs +to know is its own name, and optionally it should know the addresses of +some other nodes in the network to discover other nodes. -In addition to C pairs allowed in resolved noderefs, the -following forms are supported: +The key/value pairs are basically the same ones as documented for the +F command line utility (sans the set/del prefix). + +This function configures a node - it must be called exactly once (or +never) before calling other AnyEvent::MP functions. =over 4 -=item the empty string +=item step 1, gathering configuration from profiles + +The function first looks up a profile in the aemp configuration (see the +L commandline utility). The profile name can be specified via the +named C parameter or can simply be the first parameter). If it is +missing, then the nodename (F) will be used as profile name. + +The profile data is then gathered as follows: + +First, all remaining key => value pairs (all of which are conveniently +undocumented at the moment) will be interpreted as configuration +data. Then they will be overwritten by any values specified in the global +default configuration (see the F utility), then the chain of +profiles chosen by the profile name (and any C attributes). + +That means that the values specified in the profile have highest priority +and the values specified directly via C have lowest priority, +and can only be used to specify defaults. + +If the profile specifies a node ID, then this will become the node ID of +this process. If not, then the profile name will be used as node ID. The +special node ID of C will be replaced by a random node ID. + +=item step 2, bind listener sockets + +The next step is to look up the binds in the profile, followed by binding +aemp protocol listeners on all binds specified (it is possible and valid +to have no binds, meaning that the node cannot be contacted form the +outside. This means the node cannot talk to other nodes that also have no +binds, but it can still talk to all "normal" nodes). + +If the profile does not specify a binds list, then a default of C<*> is +used, meaning the node will bind on a dynamically-assigned port on every +local IP address it finds. + +=item step 3, connect to seed nodes + +As the last step, the seeds list from the profile is passed to the +L module, which will then use it to keep +connectivity with at least one node at any point in time. -An empty-string component gets resolved as if the default port (4040) was -specified. +=back -=item naked port numbers (e.g. C<1234>) +Example: become a distributed node using the local node name as profile. +This should be the most common form of invocation for "daemon"-type nodes. -These are resolved by prepending the local nodename and a colon, to be -further resolved. + configure -=item hostnames (e.g. C, C) +Example: become an anonymous node. This form is often used for commandline +clients. -These are resolved by using AnyEvent::DNS to resolve them, optionally -looking up SRV records for the C port, if no port was -specified. + configure nodeid => "anon/"; -=back +Example: configure a node using a profile called seed, which si suitable +for a seed node as it binds on all local addresses on a fixed port (4040, +customary for aemp). + + # use the aemp commandline utility + # aemp profile seed nodeid anon/ binds '*:4040' + + # then use it + configure profile => "seed"; + + # or simply use aemp from the shell again: + # aemp run profile seed + + # or provide a nicer-to-remember nodeid + # aemp run profile seed nodeid "$(hostname)" =item $SELF Contains the current port id while executing C callbacks or C blocks. -=item SELF, %SELF, @SELF... +=item *SELF, SELF, %SELF, @SELF... Due to some quirks in how perl exports variables, it is impossible to -just export C<$SELF>, all the symbols called C are exported by this +just export C<$SELF>, all the symbols named C are exported by this module, but only C<$SELF> is currently used. -=item snd $portid, type => @data +=item snd $port, type => @data -=item snd $portid, @msg +=item snd $port, @msg -Send the given message to the given port ID, which can identify either -a local or a remote port, and can be either a string or soemthignt hat -stringifies a sa port ID (such as a port object :). +Send the given message to the given port, which can identify either a +local or a remote port, and must be a port ID. -While the message can be about anything, it is highly recommended to use a -string as first element (a portid, or some word that indicates a request -type etc.). - -The message data effectively becomes read-only after a call to this -function: modifying any argument is not allowed and can cause many -problems. +While the message can be almost anything, it is highly recommended to +use a string as first element (a port ID, or some word that indicates a +request type etc.) and to consist if only simple perl values (scalars, +arrays, hashes) - if you think you need to pass an object, think again. + +The message data logically becomes read-only after a call to this +function: modifying any argument (or values referenced by them) is +forbidden, as there can be considerable time between the call to C +and the time the message is actually being serialised - in fact, it might +never be copied as within the same process it is simply handed to the +receiving port. The type of data you can transfer depends on the transport protocol: when JSON is used, then only strings, numbers and arrays and hashes consisting of those are allowed (no objects). When Storable is used, then anything that Storable can serialise and deserialise is allowed, and for the local -node, anything can be passed. - -=item kil $portid[, @reason] - -Kill the specified port with the given C<@reason>. - -If no C<@reason> is specified, then the port is killed "normally" (linked -ports will not be kileld, or even notified). - -Otherwise, linked ports get killed with the same reason (second form of -C, see below). +node, anything can be passed. Best rely only on the common denominator of +these. -Runtime errors while evaluating C callbacks or inside C blocks -will be reported as reason C<< die => $@ >>. - -Transport/communication errors are reported as C<< transport_error => -$message >>. - -=item $guard = mon $portid, $cb->(@reason) - -=item $guard = mon $portid, $otherport - -=item $guard = mon $portid, $otherport, @msg - -Monitor the given port and do something when the port is killed. - -In the first form, the callback is simply called with any number -of C<@reason> elements (no @reason means that the port was deleted -"normally"). Note also that I<< the callback B never die >>, so use -C if unsure. - -In the second form, the other port will be C'ed with C<@reason>, iff -a @reason was specified, i.e. on "normal" kils nothing happens, while -under all other conditions, the other port is killed with the same reason. - -In the last form, a message of the form C<@msg, @reason> will be C. +=item $local_port = port -Example: call a given callback when C<$port> is killed. +Create a new local port object and returns its port ID. Initially it has +no callbacks set and will throw an error when it receives messages. - mon $port, sub { warn "port died because of <@_>\n" }; +=item $local_port = port { my @msg = @_ } -Example: kill ourselves when C<$port> is killed abnormally. +Creates a new local port, and returns its ID. Semantically the same as +creating a port and calling C on it. - mon $port, $self; +The block will be called for every message received on the port, with the +global variable C<$SELF> set to the port ID. Runtime errors will cause the +port to be Ced. The message will be passed as-is, no extra argument +(i.e. no port ID) will be passed to the callback. -Example: send us a restart message another C<$port> is killed. +If you want to stop/destroy the port, simply C it: - mon $port, $self => "restart"; + my $port = port { + my @msg = @_; + ... + kil $SELF; + }; =cut -sub mon { - my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift); - - my $node = $NODE{$noderef} || add_node $noderef; - - #TODO: ports must not be references - if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) { - if (@_) { - # send a kill info message - my (@msg) = ($cb, @_); - $cb = sub { snd @msg, @_ }; - } else { - # simply kill other port - my $port = $cb; - $cb = sub { kil $port, @_ if @_ }; - } - } - - $node->monitor ($port, $cb); +sub rcv($@); - defined wantarray - and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } +sub _kilme { + die "received message on port without callback"; } -=item $guard = mon_guard $port, $ref, $ref... - -Monitors the given C<$port> and keeps the passed references. When the port -is killed, the references will be freed. - -Optionally returns a guard that will stop the monitoring. +sub port(;&) { + my $id = "$UNIQ." . $ID++; + my $port = "$NODE#$id"; -This function is useful when you create e.g. timers or other watchers and -want to free them when the port gets killed: + rcv $port, shift || \&_kilme; - $port->rcv (start => sub { - my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { - undef $timer if 0.9 < rand; - }); - }); - -=cut + $port +} -sub mon_guard { - my ($port, @refs) = @_; +=item rcv $local_port, $callback->(@msg) - mon $port, sub { 0 && @refs } -} +Replaces the default callback on the specified port. There is no way to +remove the default callback: use C to disable it, or better +C the port when it is no longer needed. -=item lnk $port1, $port2 +The global C<$SELF> (exported by this module) contains C<$port> while +executing the callback. Runtime errors during callback execution will +result in the port being Ced. -Link two ports. This is simply a shorthand for: +The default callback received all messages not matched by a more specific +C match. - mon $port1, $port2; - mon $port2, $port1; +=item rcv $local_port, tag => $callback->(@msg_without_tag), ... -It means that if either one is killed abnormally, the other one gets -killed as well. +Register (or replace) callbacks to be called on messages starting with the +given tag on the given port (and return the port), or unregister it (when +C<$callback> is C<$undef> or missing). There can only be one callback +registered for each tag. -=item $local_port = port +The original message will be passed to the callback, after the first +element (the tag) has been removed. The callback will use the same +environment as the default callback (see above). -Create a new local port object that supports message matching. +Example: create a port and bind receivers on it in one go. -=item $portid = port { my @msg = @_; $finished } + my $port = rcv port, + msg1 => sub { ... }, + msg2 => sub { ... }, + ; -Creates a "mini port", that is, a very lightweight port without any -pattern matching behind it, and returns its ID. +Example: create a port, bind receivers and send it in a message elsewhere +in one go: -The block will be called for every message received on the port. When the -callback returns a true value its job is considered "done" and the port -will be destroyed. Otherwise it will stay alive. + snd $otherport, reply => + rcv port, + msg1 => sub { ... }, + ... + ; -The message will be passed as-is, no extra argument (i.e. no port id) will -be passed to the callback. +Example: temporarily register a rcv callback for a tag matching some port +(e.g. for an rpc reply) and unregister it after a message was received. -If you need the local port id in the callback, this works nicely: + rcv $port, $otherport => sub { + my @reply = @_; - my $port; $port = miniport { - snd $otherport, reply => $port; + rcv $SELF, $otherport; }; =cut -sub port(;&) { - my $id = "$UNIQ." . $ID++; - my $port = "$NODE#$id"; - - if (@_) { - my $cb = shift; - $PORT{$id} = sub { - local $SELF = $port; - eval { - &$cb - and kil $id; - }; - _self_die if $@; - }; - } else { - my $self = bless { - id => "$NODE#$id", - }, "AnyEvent::MP::Port"; - - $PORT_DATA{$id} = $self; - $PORT{$id} = sub { - local $SELF = $port; - - eval { - for (@{ $self->{rc0}{$_[0]} }) { - $_ && &{$_->[0]} - && undef $_; - } - - for (@{ $self->{rcv}{$_[0]} }) { - $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1] - && &{$_->[0]} - && undef $_; - } - - for (@{ $self->{any} }) { - $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1] - && &{$_->[0]} - && undef $_; - } - }; - _self_die if $@; - }; - } - - $port -} +sub rcv($@) { + my $port = shift; + my ($nodeid, $portid) = split /#/, $port, 2; -=item reg $portid, $name + $NODE{$nodeid} == $NODE{""} + or Carp::croak "$port: rcv can only be called on local ports, caught"; -Registers the given port under the name C<$name>. If the name already -exists it is replaced. + while (@_) { + if (ref $_[0]) { + if (my $self = $PORT_DATA{$portid}) { + "AnyEvent::MP::Port" eq ref $self + or Carp::croak "$port: rcv can only be called on message matching ports, caught"; + + $self->[0] = shift; + } else { + my $cb = shift; + $PORT{$portid} = sub { + local $SELF = $port; + eval { &$cb }; _self_die if $@; + }; + } + } elsif (defined $_[0]) { + my $self = $PORT_DATA{$portid} ||= do { + my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; + + $PORT{$portid} = sub { + local $SELF = $port; + + if (my $cb = $self->[1]{$_[0]}) { + shift; + eval { &$cb }; _self_die if $@; + } else { + &{ $self->[0] }; + } + }; -A port can only be registered under one well known name. + $self + }; -A port automatically becomes unregistered when it is killed. + "AnyEvent::MP::Port" eq ref $self + or Carp::croak "$port: rcv can only be called on message matching ports, caught"; -=cut + my ($tag, $cb) = splice @_, 0, 2; -sub reg(@) { - my ($portid, $name) = @_; + if (defined $cb) { + $self->[1]{$tag} = $cb; + } else { + delete $self->[1]{$tag}; + } + } + } - $REG{$name} = $portid; + $port } -=item rcv $portid, tagstring => $callback->(@msg), ... +=item peval $port, $coderef[, @args] -=item rcv $portid, $smartmatch => $callback->(@msg), ... +Evaluates the given C<$codref> within the contetx of C<$port>, that is, +when the code throews an exception the C<$port> will be killed. -=item rcv $portid, [$smartmatch...] => $callback->(@msg), ... +Any remaining args will be passed to the callback. Any return values will +be returned to the caller. -Register callbacks to be called on matching messages on the given port. +This is useful when you temporarily want to execute code in the context of +a port. -The callback has to return a true value when its work is done, after -which is will be removed, or a false value in which case it will stay -registered. +Example: create a port and run some initialisation code in it's context. -The global C<$SELF> (exported by this module) contains C<$portid> while -executing the callback. + my $port = port { ... }; -Runtime errors wdurign callback execution will result in the port being -Ced. - -If the match is an array reference, then it will be matched against the -first elements of the message, otherwise only the first element is being -matched. - -Any element in the match that is specified as C<_any_> (a function -exported by this module) matches any single element of the message. - -While not required, it is highly recommended that the first matching -element is a string identifying the message. The one-string-only match is -also the most efficient match (by far). + peval $port, sub { + init + or die "unable to init"; + }; =cut -sub rcv($@) { - my ($noderef, $port) = split /#/, shift, 2; - - ($NODE{$noderef} || add_node $noderef) == $NODE{""} - or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught"; - - my $self = $PORT_DATA{$port} - or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; - - "AnyEvent::MP::Port" eq ref $self - or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; - - while (@_) { - my ($match, $cb) = splice @_, 0, 2; +sub peval($$) { + local $SELF = shift; + my $cb = shift; - if (!ref $match) { - push @{ $self->{rc0}{$match} }, [$cb]; - } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { - my ($type, @match) = @$match; - @match - ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match] - : push @{ $self->{rc0}{$match->[0]} }, [$cb]; - } else { - push @{ $self->{any} }, [$cb, $match]; - } + if (wantarray) { + my @res = eval { &$cb }; + _self_die if $@; + @res + } else { + my $res = eval { &$cb }; + _self_die if $@; + $res } } @@ -453,6 +496,9 @@ closure is executed, sets up the environment in the same way as in C callbacks, i.e. runtime errors will cause the port to get Ced. +The effect is basically as if it returned C<< sub { peval $SELF, sub { +BLOCK } } >>. + This is useful when you register callbacks from C callbacks: rcv delayed_reply => sub { @@ -485,78 +531,304 @@ } } -=back +=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies -=head1 FUNCTIONS FOR NODES +=item $guard = mon $port, $rcvport # kill $rcvport when $port dies -=over 4 +=item $guard = mon $port # kill $SELF when $port dies -=item become_public $noderef +=item $guard = mon $port, $rcvport, @msg # send a message when $port dies -Tells the node to become a public node, i.e. reachable from other nodes. +Monitor the given port and do something when the port is killed or +messages to it were lost, and optionally return a guard that can be used +to stop monitoring again. -The first argument is the (unresolved) node reference of the local node -(if missing then the empty string is used). +In the first form (callback), the callback is simply called with any +number of C<@reason> elements (no @reason means that the port was deleted +"normally"). Note also that I<< the callback B never die >>, so use +C if unsure. -It is quite common to not specify anything, in which case the local node -tries to listen on the default port, or to only specify a port number, in -which case AnyEvent::MP tries to guess the local addresses. +In the second form (another port given), the other port (C<$rcvport>) +will be C'ed with C<@reason>, if a @reason was specified, i.e. on +"normal" kils nothing happens, while under all other conditions, the other +port is killed with the same reason. + +The third form (kill self) is the same as the second form, except that +C<$rvport> defaults to C<$SELF>. + +In the last form (message), a message of the form C<@msg, @reason> will be +C. + +Monitoring-actions are one-shot: once messages are lost (and a monitoring +alert was raised), they are removed and will not trigger again. + +As a rule of thumb, monitoring requests should always monitor a port from +a local port (or callback). The reason is that kill messages might get +lost, just like any other message. Another less obvious reason is that +even monitoring requests can get lost (for example, when the connection +to the other node goes down permanently). When monitoring a port locally +these problems do not exist. + +C effectively guarantees that, in the absence of hardware failures, +after starting the monitor, either all messages sent to the port will +arrive, or the monitoring action will be invoked after possible message +loss has been detected. No messages will be lost "in between" (after +the first lost message no further messages will be received by the +port). After the monitoring action was invoked, further messages might get +delivered again. + +Inter-host-connection timeouts and monitoring depend on the transport +used. The only transport currently implemented is TCP, and AnyEvent::MP +relies on TCP to detect node-downs (this can take 10-15 minutes on a +non-idle connection, and usually around two hours for idle connections). + +This means that monitoring is good for program errors and cleaning up +stuff eventually, but they are no replacement for a timeout when you need +to ensure some maximum latency. + +Example: call a given callback when C<$port> is killed. + + mon $port, sub { warn "port died because of <@_>\n" }; + +Example: kill ourselves when C<$port> is killed abnormally. + + mon $port; + +Example: send us a restart message when another C<$port> is killed. + + mon $port, $self => "restart"; =cut -=back +sub mon { + my ($nodeid, $port) = split /#/, shift, 2; -=head1 NODE MESSAGES + my $node = $NODE{$nodeid} || add_node $nodeid; -Nodes understand the following messages sent to them. Many of them take -arguments called C<@reply>, which will simply be used to compose a reply -message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and -the remaining arguments are simply the message data. + my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; -While other messages exist, they are not public and subject to change. + unless (ref $cb) { + if (@_) { + # send a kill info message + my (@msg) = ($cb, @_); + $cb = sub { snd @msg, @_ }; + } else { + # simply kill other port + my $port = $cb; + $cb = sub { kil $port, @_ if @_ }; + } + } -=over 4 + $node->monitor ($port, $cb); + + defined wantarray + and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) +} + +=item $guard = mon_guard $port, $ref, $ref... + +Monitors the given C<$port> and keeps the passed references. When the port +is killed, the references will be freed. + +Optionally returns a guard that will stop the monitoring. + +This function is useful when you create e.g. timers or other watchers and +want to free them when the port gets killed (note the use of C): + + $port->rcv (start => sub { + my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { + undef $timer if 0.9 < rand; + }); + }); =cut -=item lookup => $name, @reply +sub mon_guard { + my ($port, @refs) = @_; + + #TODO: mon-less form? + + mon $port, sub { 0 && @refs } +} + +=item kil $port[, @reason] + +Kill the specified port with the given C<@reason>. + +If no C<@reason> is specified, then the port is killed "normally" - +monitor callback will be invoked, but the kil will not cause linked ports +(C form) to get killed. + +If a C<@reason> is specified, then linked ports (C +form) get killed with the same reason. + +Runtime errors while evaluating C callbacks or inside C blocks +will be reported as reason C<< die => $@ >>. + +Transport/communication errors are reported as C<< transport_error => +$message >>. + +=cut -Replies with the port ID of the specified well-known port, or C. +=item $port = spawn $node, $initfunc[, @initdata] -=item devnull => ... +Creates a port on the node C<$node> (which can also be a port ID, in which +case it's the node where that port resides). -Generic data sink/CPU heat conversion. +The port ID of the newly created port is returned immediately, and it is +possible to immediately start sending messages or to monitor the port. -=item relay => $port, @msg +After the port has been created, the init function is called on the remote +node, in the same context as a C callback. This function must be a +fully-qualified function name (e.g. C). To +specify a function in the main program, use C<::name>. -Simply forwards the message to the given port. +If the function doesn't exist, then the node tries to C +the package, then the package above the package and so on (e.g. +C, C, C) until the function +exists or it runs out of package names. -=item eval => $string[ @reply] +The init function is then called with the newly-created port as context +object (C<$SELF>) and the C<@initdata> values as arguments. It I +call one of the C functions to set callbacks on C<$SELF>, otherwise +the port might not get created. -Evaluates the given string. If C<@reply> is given, then a message of the -form C<@reply, $@, @evalres> is sent. +A common idiom is to pass a local port, immediately monitor the spawned +port, and in the remote init function, immediately monitor the passed +local port. This two-way monitoring ensures that both ports get cleaned up +when there is a problem. -Example: crash another node. +C guarantees that the C<$initfunc> has no visible effects on the +caller before C returns (by delaying invocation when spawn is +called for the local node). - snd $othernode, eval => "exit"; +Example: spawn a chat server port on C<$othernode>. -=item time => @reply + # this node, executed from within a port context: + my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; + mon $server; -Replies the the current node time to C<@reply>. + # init function on C<$othernode> + sub connect { + my ($srcport) = @_; -Example: tell the current node to send the current time to C<$myport> in a -C message. + mon $srcport; - snd $NODE, time => $myport, timereply => 1, 2; - # => snd $myport, timereply => 1, 2,