Node

Functions related to VM nodes.

Some of the functions in this module are inlined by the compiler, similar to functions in the Kernel module and they are explicitly marked in their docs as "inlined by the compiler". For more information about inlined functions, check out the Kernel module.

Summary

Functions

alive?(): Returns true if the local node is alive.
connect(node): Establishes a connection to node.
disconnect(node): Forces the disconnection of a node.
get_cookie(): Returns the magic cookie of the local node.
list(): Returns a list of all visible nodes in the system, excluding the local node.
list(args): Returns a list of nodes according to argument given.
monitor(node, flag): Monitors the status of the node.
monitor(node, flag, options): Behaves as monitor/2 except that it allows an extra option to be given, namely :allow_passive_connect.
ping(node): Tries to set up a connection to node.
self(): Returns the current node.
set_cookie(node \\ Node.self(), cookie): Sets the magic cookie of node to the atom cookie.
spawn(node, fun): Returns the PID of a new process started by the application of fun on node. If node does not exist, a useless PID is returned.
spawn(node, fun, opts): Returns the PID of a new process started by the application of fun on node.
spawn(node, module, fun, args): Returns the PID of a new process started by the application of module.function(args) on node.
spawn(node, module, fun, args, opts): Returns the PID of a new process started by the application of module.function(args) on node.
spawn_link(node, fun): Returns the PID of a new linked process started by the application of fun on node.
spawn_link(node, module, fun, args): Returns the PID of a new linked process started by the application of module.function(args) on node.
start(name, type \\ :longnames, tick_time \\ 15000): Turns a non-distributed node into a distributed node.
stop(): Turns a distributed node into a non-distributed node.

Types

state()

Specs

state() :: :visible | :hidden | :connected | :this | :known

t()

Specs

t() :: node()

Functions

alive?()

Specs

alive?() :: boolean()

Returns true if the local node is alive.

That is, if the node can be part of a distributed system.

connect(node)

Specs

connect(t()) :: boolean() | :ignored

Establishes a connection to node.

Returns true if successful, false if not, and the atom :ignored if the local node is not alive.

For more information, see :net_kernel.connect_node/1.

disconnect(node)

Specs

disconnect(t()) :: boolean() | :ignored

Forces the disconnection of a node.

This will appear to the node as if the local node has crashed. This function is mainly used in the Erlang network authentication protocols. Returns true if disconnection succeeds, otherwise false. If the local node is not alive, the function returns :ignored.

For more information, see :erlang.disconnect_node/1.

get_cookie()

Specs

get_cookie() :: atom()

Returns the magic cookie of the local node.

Returns the cookie if the node is alive, otherwise :nocookie.

list()

Specs

list() :: [t()]

Returns a list of all visible nodes in the system, excluding the local node.

Same as list(:visible).

Inlined by the compiler.

list(args)

Specs

list(state() | [state()]) :: [t()]

Returns a list of nodes according to argument given.

The result returned when the argument is a list, is the list of nodes satisfying the disjunction(s) of the list elements.

For more information, see :erlang.nodes/1.

Inlined by the compiler.

monitor(node, flag)

Specs

monitor(t(), boolean()) :: true

Monitors the status of the node.

If flag is true, monitoring is turned on. If flag is false, monitoring is turned off.

For more information, see :erlang.monitor_node/2.

For monitoring status changes of all nodes, see :net_kernel.monitor_nodes/3.

monitor(node, flag, options)

Specs

monitor(t(), boolean(), [:allow_passive_connect]) :: true

Behaves as monitor/2 except that it allows an extra option to be given, namely :allow_passive_connect.

For more information, see :erlang.monitor_node/3.

For monitoring status changes of all nodes, see :net_kernel.monitor_nodes/3.

ping(node)

Specs

ping(t()) :: :pong | :pang

Tries to set up a connection to node.

Returns :pang if it fails, or :pong if it is successful.

Examples

iex> Node.ping(:unknown_node)
:pang

self()

Specs

self() :: t()

Returns the current node.

It returns the same as the built-in node().

set_cookie(node \\ Node.self(), cookie)

Specs

set_cookie(t(), atom()) :: true

Sets the magic cookie of node to the atom cookie.

The default node is Node.self/0, the local node. If node is the local node, the function also sets the cookie of all other unknown nodes to cookie.

This function will raise FunctionClauseError if the given node is not alive.

spawn(node, fun)

Specs

spawn(t(), (() -> any())) :: pid()

Returns the PID of a new process started by the application of fun on node. If node does not exist, a useless PID is returned.

For the list of available options, see :erlang.spawn/2.

Inlined by the compiler.

spawn(node, fun, opts)

Specs

spawn(t(), (() -> any()), Process.spawn_opts()) :: pid() | {pid(), reference()}

Returns the PID of a new process started by the application of fun on node.

If node does not exist, a useless PID is returned.

For the list of available options, see :erlang.spawn_opt/3.

Inlined by the compiler.

spawn(node, module, fun, args)

Specs

spawn(t(), module(), atom(), [any()]) :: pid()

Returns the PID of a new process started by the application of module.function(args) on node.

If node does not exist, a useless PID is returned.

For the list of available options, see :erlang.spawn/4.

Inlined by the compiler.

spawn(node, module, fun, args, opts)

Specs

spawn(t(), module(), atom(), [any()], Process.spawn_opts()) ::
  pid() | {pid(), reference()}

Returns the PID of a new process started by the application of module.function(args) on node.

If node does not exist, a useless PID is returned.

For the list of available options, see :erlang.spawn/5.

Inlined by the compiler.

spawn_link(node, fun)

Specs

spawn_link(t(), (() -> any())) :: pid()

Returns the PID of a new linked process started by the application of fun on node.

A link is created between the calling process and the new process, atomically. If node does not exist, a useless PID is returned (and due to the link, an exit signal with exit reason :noconnection will be received).

Inlined by the compiler.

spawn_link(node, module, fun, args)

Specs

spawn_link(t(), module(), atom(), [any()]) :: pid()

Returns the PID of a new linked process started by the application of module.function(args) on node.

Inlined by the compiler.

start(name, type \\ :longnames, tick_time \\ 15000)

Specs

start(node(), :longnames | :shortnames, non_neg_integer()) ::
  {:ok, pid()} | {:error, term()}

Turns a non-distributed node into a distributed node.

This functionality starts the :net_kernel and other related processes.

This function is rarely invoked in practice. Instead, nodes are named and started via the command line by using the --sname and --name flags. If you need to use this function to dynamically name a node, please make sure the epmd operating system process is running by calling epmd -daemon.

Invoking this function when the distribution has already been started, either via the command line interface or dynamically, will return an error.

Examples

{:ok, pid} = Node.start(:example, :shortnames, 15000)

stop()

Specs

stop() :: :ok | {:error, :not_allowed | :not_found}

Turns a distributed node into a non-distributed node.

For other nodes in the network, this is the same as the node going down. Only possible when the node was started with Node.start/3, otherwise returns {:error, :not_allowed}. Returns {:error, :not_found} if the local node is not alive.