NAME AnyEvent::MP - multi-processing/message-passing framework SYNOPSIS use AnyEvent::MP; $NODE # contains this node's noderef NODE # returns this node's noderef NODE $port # returns the noderef of the port $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" # ports are message endpoints # sending messages snd $port, type => data...; snd $port, @msg; snd @msg_with_first_element_being_a_port; # creating/using ports, the simple way my $simple_port = port { my @msg = @_; 0 }; # creating/using ports, tagged message matching my $port = port; rcv $port, ping => sub { snd $_[0], "pong"; 0 }; rcv $port, pong => sub { warn "pong received\n"; 0 }; # create a port on another node my $port = spawn $node, $initfunc, @initdata; # monitoring mon $port, $cb->(@msg) # callback is invoked on death mon $port, $otherport # kill otherport on abnormal death mon $port, $otherport, @msg # send message on death CURRENT STATUS AnyEvent::MP - stable API, should work AnyEvent::MP::Intro - outdated AnyEvent::MP::Kernel - WIP AnyEvent::MP::Transport - mostly stable stay tuned. 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. For an introduction to this module family, see the AnyEvent::MP::Intro 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! CONCEPTS port A port is something you can send messages to (with the "snd" function). Ports allow you to register "rcv" handlers that can match all or just some messages. Messages will not be queued. port id - "noderef#portname" A port ID is the concatenation of a noderef, a hash-mark ("#") 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. 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 ports. Nodes are either private (single-process only), slaves (connected to a master node only) or public nodes (connectable from unrelated nodes). noderef - "host:port,host:port...", "id@noderef", "id" 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 "address:port" pairs (for TCP/IP, other protocols might look different). 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. VARIABLES/FUNCTIONS $thisnode = NODE / $NODE The "NODE" function returns, and the $NODE variable contains the noderef of the local node. The value is initialised by a call to "initialise_node". $noderef = node_of $port Extracts and returns the noderef from a port ID or a noderef. initialise_node $noderef, $seednode, $seednode... initialise_node "slave/", $master, $master... 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. 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 "undef" then the current nodename will be used instead) to find the relevant configuration profile (see aemp). If none is found then the default configuration is used. The configuration supplies additional seed/master nodes and can override the actual noderef. There are two types of networked nodes, public nodes and slave nodes: public nodes For public nodes, $noderef (supplied either directly to "initialise_node" 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 $seednodes that are specified. Seednodes are optional and can be used to quickly bootstrap the node into an existing network. slave nodes When the $noderef (either as given or overriden by the config file) is the special string "slave/", 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. 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 "aemp" 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 "aemp". This form is often used for commandline clients. initialise_node "slave/"; Example: become a slave node to any of the specified master servers. This form is also often used for commandline clients. 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 4041. initialise_node 4041; Example: become a public node, only visible on localhost port 4044. initialise_node "localhost:4044"; $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 "address:port" pairs allowed in resolved noderefs, the following forms are supported: the empty string An empty-string component gets resolved as if the default port (4040) was specified. naked port numbers (e.g. 1234) These are resolved by prepending the local nodename and a colon, to be further resolved. hostnames (e.g. "localhost:1234", "localhost") These are resolved by using AnyEvent::DNS to resolve them, optionally looking up SRV records for the "aemp=4040" port, if no port was specified. $SELF Contains the current port id while executing "rcv" callbacks or "psub" blocks. SELF, %SELF, @SELF... Due to some quirks in how perl exports variables, it is impossible to just export $SELF, all the symbols called "SELF" are exported by this module, but only $SELF is currently used. snd $port, type => @data 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. 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. 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. $local_port = port 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. $local_port = port { my @msg = @_ } Creates a new local port, and returns its ID. Semantically the same as creating a port and calling "rcv $port, $callback" on it. The block will be called for every message received on the port, with the global variable $SELF set to the port ID. Runtime errors will cause the port to be "kil"ed. The message will be passed as-is, no extra argument (i.e. no port ID) will be passed to the callback. If you want to stop/destroy the port, simply "kil" it: my $port = port { my @msg = @_; ... kil $SELF; }; rcv $local_port, $callback->(@msg) Replaces the default callback on the specified port. There is no way to remove the default callback: use "sub { }" to disable it, or better "kil" the port when it is no longer needed. The global $SELF (exported by this module) contains $port while executing the callback. Runtime errors during callback execution will result in the port being "kil"ed. The default callback received all messages not matched by a more specific "tag" match. rcv $local_port, tag => $callback->(@msg_without_tag), ... 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 $callback is $undef or missing). There can only be one callback registered for each tag. 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). Example: create a port and bind receivers on it in one go. my $port = rcv port, msg1 => sub { ... }, msg2 => sub { ... }, ; Example: create a port, bind receivers and send it in a message elsewhere in one go: snd $otherport, reply => rcv port, msg1 => sub { ... }, ... ; Example: temporarily register a rcv callback for a tag matching some port (e.g. for a rpc reply) and unregister it after a message was received. rcv $port, $otherport => sub { my @reply = @_; rcv $SELF, $otherport; }; $closure = psub { BLOCK } Remembers $SELF and creates a closure out of the BLOCK. When the closure is executed, sets up the environment in the same way as in "rcv" callbacks, i.e. runtime errors will cause the port to get "kil"ed. This is useful when you register callbacks from "rcv" callbacks: rcv delayed_reply => sub { my ($delay, @reply) = @_; my $timer = AE::timer $delay, 0, psub { snd @reply, $SELF; }; }; $guard = mon $port, $cb->(@reason) $guard = mon $port, $rcvport $guard = mon $port $guard = mon $port, $rcvport, @msg Monitor the given port and do something when the port is killed or messages to it were lost, and optionally return a guard that can be used to stop monitoring again. "mon" effectively guarantees that, in the absence of hardware failures, that after starting the monitor, either all messages sent to the port will arrive, or the monitoring action will be invoked after possible message loss has been detected. No messages will be lost "in between" (after the first lost message no further messages will be received by the port). After the monitoring action was invoked, further messages might get delivered again. In the first form (callback), the callback is simply called with any number of @reason elements (no @reason means that the port was deleted "normally"). Note also that *the callback must never die*, so use "eval" if unsure. In the second form (another port given), the other port ($rcvport) will be "kil"'ed with @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. The third form (kill self) is the same as the second form, except that $rvport defaults to $SELF. In the last form (message), a message of the form "@msg, @reason" will be "snd". 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 exmaple, when the connection to the other node goes down permanently). When monitoring a port locally these problems do not exist. Example: call a given callback when $port is killed. mon $port, sub { warn "port died because of <@_>\n" }; Example: kill ourselves when $port is killed abnormally. mon $port; Example: send us a restart message when another $port is killed. mon $port, $self => "restart"; $guard = mon_guard $port, $ref, $ref... Monitors the given $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: $port->rcv (start => sub { my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { undef $timer if 0.9 < rand; }); }); kil $port[, @reason] Kill the specified port with the given @reason. If no @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 "mon", see below). Runtime errors while evaluating "rcv" callbacks or inside "psub" blocks will be reported as reason "die => $@". Transport/communication errors are reported as "transport_error => $message". $port = spawn $node, $initfunc[, @initdata] Creates a port on the node $node (which can also be a port ID, in which case it's the node where that port resides). The port ID of the newly created port is return immediately, and it is permissible to immediately start sending messages or monitor the port. After the port has been created, the init function is called. This function must be a fully-qualified function name (e.g. "MyApp::Chat::Server::init"). To specify a function in the main program, use "::name". If the function doesn't exist, then the node tries to "require" the package, then the package above the package and so on (e.g. "MyApp::Chat::Server", "MyApp::Chat", "MyApp") until the function exists or it runs out of package names. The init function is then called with the newly-created port as context object ($SELF) and the @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. Example: spawn a chat server port on $othernode. # this node, executed from within a port context: my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; mon $server; # init function on C<$othernode> sub connect { my ($srcport) = @_; mon $srcport; rcv $SELF, sub { ... }; } NODE MESSAGES Nodes understand the following messages sent to them. Many of them take arguments called @reply, which will simply be used to compose a reply message - $reply[0] is the port to reply to, $reply[1] the type and the remaining arguments are simply the message data. While other messages exist, they are not public and subject to change. lookup => $name, @reply Replies with the port ID of the specified well-known port, or "undef". devnull => ... Generic data sink/CPU heat conversion. relay => $port, @msg Simply forwards the message to the given port. eval => $string[ @reply] Evaluates the given string. If @reply is given, then a message of the form "@reply, $@, @evalres" is sent. Example: crash another node. snd $othernode, eval => "exit"; time => @reply Replies the the current node time to @reply. Example: tell the current node to send the current time to $myport in a "timereply" message. snd $NODE, time => $myport, timereply => 1, 2; # => snd $myport, timereply => 1, 2,