--- AnyEvent-MP/MP.pm 2009/08/14 23:17:17 1.55 +++ AnyEvent-MP/MP.pm 2009/08/28 23:06:33 1.68 @@ -13,9 +13,7 @@ $SELF # receiving/own port id in rcv callbacks # initialise the node so it can send/receive messages - initialise_node; # -OR- - initialise_node "localhost:4040"; # -OR- - initialise_node "slave/", "localhost:4040" + initialise_node; # ports are message endpoints @@ -44,8 +42,10 @@ AnyEvent::MP - stable API, should work AnyEvent::MP::Intro - outdated - AnyEvent::MP::Kernel - WIP - AnyEvent::MP::Transport - mostly stable + AnyEvent::MP::Kernel - mostly stable + AnyEvent::MP::Global - mostly stable + AnyEvent::MP::Node - mostly stable, but internal anyways + AnyEvent::MP::Transport - mostly stable, but internal anyways stay tuned. @@ -54,14 +54,12 @@ 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. +manual page and the examples under F. -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! +At the moment, this module family is a bit underdocumented. =head1 CONCEPTS @@ -72,38 +70,52 @@ 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 will not be queued. +some messages. Messages send to ports will not be queued, regardless of +anything was listening for them or not. -=item port id - C +=item port ID - C -A port ID is 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 its node -reference. +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, -which provides nodes to manage each other remotely, and to create new +which enables nodes to manage each other remotely, and to create new ports. -Nodes are either private (single-process only), slaves (connected to a -master node only) or public nodes (connectable from unrelated nodes). - -=item noderef - C, C, C - -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). - -This recipe is simply a comma-separated list of C pairs (for -TCP/IP, other protocols might look different). +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-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 seeds - C + +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. + +Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes +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. -Node references come in two flavours: resolved (containing only numerical -addresses) or unresolved (where hostnames are used instead of addresses). - -Before using an unresolved node reference in a message you first have to -resolve it. +Apart from being sued for seeding, seednodes are not special in any way - +every public node can be a seednode. =back @@ -128,9 +140,9 @@ our $VERSION = $AnyEvent::MP::Kernel::VERSION; our @EXPORT = qw( - NODE $NODE *SELF node_of _any_ - resolve_node initialise_node - snd rcv mon kil reg psub spawn + NODE $NODE *SELF node_of after + initialise_node + snd rcv mon mon_guard kil reg psub spawn port ); @@ -144,156 +156,101 @@ =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. - -=item $noderef = node_of $port +The C function returns, and the C<$NODE> variable contains, the node +ID of the node running in the current process. This value is initialised by +a call to C. -Extracts and returns the noderef from a port ID or a noderef. +=item $nodeid = node_of $port -=item initialise_node $noderef, $seednode, $seednode... +Extracts and returns the node ID from a port ID or a node ID. -=item initialise_node "slave/", $master, $master... +=item initialise_node $profile_name -Before a node can talk to other nodes on the network it has to initialise -itself - the minimum a node needs to know is it's own name, and optionally -it should know the noderefs of some other nodes in the network. +Before a node can talk to other nodes on the network (i.e. enter +"distributed mode") it has to initialise itself - the minimum a node needs +to know is its own name, and optionally it should know the addresses of +some other nodes in the network to discover other nodes. This function initialises a node - it must be called exactly once (or never) before calling other AnyEvent::MP functions. -All arguments (optionally except for the first) are noderefs, which can be -either resolved or unresolved. - -The first argument will be looked up in the configuration database first -(if it is C then the current nodename will be used instead) to find -the relevant configuration profile (see L). If none is found then -the default configuration is used. The configuration supplies additional -seed/master nodes and can override the actual noderef. +The first argument is a profile name. If it is C or missing, then +the current nodename will be used instead (i.e. F). -There are two types of networked nodes, public nodes and slave nodes: +The function then looks up the profile in the aemp configuration (see the +L commandline utility). -=over 4 - -=item public nodes - -For public nodes, C<$noderef> (supplied either directly to -C or indirectly via a profile or the nodename) must be a -noderef (possibly unresolved, in which case it will be resolved). - -After resolving, the node will bind itself on all endpoints and try to -connect to all additional C<$seednodes> that are specified. Seednodes are -optional and can be used to quickly bootstrap the node into an existing -network. - -=item slave nodes - -When the C<$noderef> (either as given or overriden by the config file) -is the special string C, then the node will become a slave -node. Slave nodes cannot be contacted from outside and will route most of -their traffic to the master node that they attach to. - -At least one additional noderef is required (either by specifying it -directly or because it is part of the configuration profile): The node -will try to connect to all of them and will become a slave attached to the -first node it can successfully connect to. - -=back - -This function will block until all nodes have been resolved and, for slave -nodes, until it has successfully established a connection to a master -server. - -Example: become a public node listening on the guessed noderef, or the one -specified via C for the current node. This should be the most common -form of invocation for "daemon"-type nodes. +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. + +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 the node ID will be +treated as if it were of the form C, which will be resolved and +used as binds list. + +Lastly, the seeds list from the profile is passed to the +L module, which will then use it to keep +connectivity with at least on of those seed nodes at any point in time. + +Example: become a distributed node listening on the guessed noderef, or +the one specified via C for the current node. This should be the +most common form of invocation for "daemon"-type nodes. initialise_node; -Example: become a slave node to any of the the seednodes specified via -C. This form is often used for commandline clients. - - initialise_node "slave/"; +Example: become an anonymous node. This form is often used for commandline +clients. -Example: become a slave node to any of the specified master servers. This -form is also often used for commandline clients. + initialise_node "anon/"; - initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net"; - -Example: become a public node, and try to contact some well-known master -servers to become part of the network. - - initialise_node undef, "master1", "master2"; - -Example: become a public node listening on port C<4041>. - - initialise_node 4041; - -Example: become a public node, only visible on localhost port 4044. +Example: become a distributed node. If there is no profile of the given +name, or no binds list was specified, resolve C and bind +on the resulting addresses. initialise_node "localhost:4044"; -=item $cv = resolve_node $noderef - -Takes an unresolved node reference that may contain hostnames and -abbreviated IDs, resolves all of them and returns a resolved node -reference. - -In addition to C pairs allowed in resolved noderefs, the -following forms are supported: - -=over 4 - -=item the empty string - -An empty-string component gets resolved as if the default port (4040) was -specified. - -=item naked port numbers (e.g. C<1234>) - -These are resolved by prepending the local nodename and a colon, to be -further resolved. - -=item hostnames (e.g. C, C) - -These are resolved by using AnyEvent::DNS to resolve them, optionally -looking up SRV records for the C port, if no port was -specified. - -=back - =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 $port, type => @data =item snd $port, @msg -Send the given message to the given port ID, which can identify either -a local or a remote port, and must be a port ID. +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 port ID, 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. +node, anything can be passed. Best rely only on the common denominator of +these. =item $local_port = port @@ -390,7 +347,7 @@ my $port = shift; my ($noderef, $portid) = split /#/, $port, 2; - ($NODE{$noderef} || add_node $noderef) == $NODE{""} + $NODE{$noderef} == $NODE{""} or Carp::croak "$port: rcv can only be called on local ports, caught"; while (@_) { @@ -479,26 +436,29 @@ } } -=item $guard = mon $port, $cb->(@reason) +=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies -=item $guard = mon $port, $rcvport +=item $guard = mon $port, $rcvport # kill $rcvport when $port dies -=item $guard = mon $port +=item $guard = mon $port # kill $SELF when $port dies -=item $guard = mon $port, $rcvport, @msg +=item $guard = mon $port, $rcvport, @msg # send a message when $port dies 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. C effectively guarantees that, in the absence of hardware failures, -that 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 +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. +Note that monitoring-actions are one-shot: once messages are lost (and a +monitoring alert was raised), they are removed and will not trigger again. + 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 @@ -569,10 +529,10 @@ 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: +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, sub { + my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { undef $timer if 0.9 < rand; }); }); @@ -591,11 +551,12 @@ 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). +If no C<@reason> is specified, then the port is killed "normally" (ports +monitoring other ports will not necessarily die because a port dies +"normally"). Otherwise, linked ports get killed with the same reason (second form of -C, see below). +C, see above). Runtime errors while evaluating C callbacks or inside C blocks will be reported as reason C<< die => $@ >>. @@ -610,13 +571,13 @@ Creates a port on the node C<$node> (which can also be a port ID, in which case it's the node where that port resides). -The port ID of the newly created port is return immediately, and it is -permissible to immediately start sending messages or monitor the port. +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. -After the port has been created, the init function is -called. This function must be a fully-qualified function name -(e.g. C). To specify a function in the main -program, use C<::name>. +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>. 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. @@ -626,9 +587,10 @@ The init function is then called with the newly-created port as context object (C<$SELF>) and the C<@initdata> values as arguments. -A common idiom is to pass your own port, monitor the spawned port, and -in the init function, monitor the original port. This two-way monitoring -ensures that both ports get cleaned up when there is a problem. +A common idiom is to pass a local port, immediately monitor the spawned +port, and in the remote init function, immediately monitor the passed +local port. This two-way monitoring ensures that both ports get cleaned up +when there is a problem. Example: spawn a chat server port on C<$othernode>. @@ -673,51 +635,29 @@ "$noderef#$id" } -=back - -=head1 NODE MESSAGES +=item after $timeout, @msg -Nodes understand the following messages sent to them. Many of them take -arguments called C<@reply>, which will simply be used to compose a reply -message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and -the remaining arguments are simply the message data. +=item after $timeout, $callback -While other messages exist, they are not public and subject to change. +Either sends the given message, or call the given callback, after the +specified number of seconds. -=over 4 +This is simply a utility function that comes in handy at times - the +AnyEvent::MP author is not convinced of the wisdom of having it, though, +so it may go away in the future. =cut -=item lookup => $name, @reply - -Replies with the port ID of the specified well-known port, or C. - -=item devnull => ... - -Generic data sink/CPU heat conversion. - -=item relay => $port, @msg - -Simply forwards the message to the given port. - -=item eval => $string[ @reply] +sub after($@) { + my ($timeout, @action) = @_; -Evaluates the given string. If C<@reply> is given, then a message of the -form C<@reply, $@, @evalres> is sent. - -Example: crash another node. - - snd $othernode, eval => "exit"; - -=item time => @reply - -Replies the the current node time to C<@reply>. - -Example: tell the current node to send the current time to C<$myport> in a -C message. - - snd $NODE, time => $myport, timereply => 1, 2; - # => snd $myport, timereply => 1, 2,