ranch/manual/ranch.md

ranch

The ranch module provides functions for starting and manipulating Ranch listeners.

Types

max_conns() = non_neg_integer() | infinity

Maximum number of connections allowed on this listener.

This is a soft limit. The actual number of connections might be slightly above the limit due to concurrency when accepting new connections. Some connections may also be removed from this count explicitly by the user code.

opt() = {ack_timeout, timeout()}

| {connection_type, worker | supervisor}
| {max_connections, max_conns()}
| {shutdown, timeout() | brutal_kill}
| {socket, any()}

Ranch-specific transport options.

These options are not passed on to the transports. They are used by Ranch while setting up the listeners.

ref() = any()

Unique name used to refer to a listener.

Exports

accept_ack(Ref) -> ok

Types:

• Ref = ref()

Acknowledge that the connection is accepted.

This function MUST be used by a connection process to inform Ranch that it initialized properly and let it perform any additional operations before the socket can be safely used.

child_spec(Ref, NbAcceptors, Transport, TransOpts, Protocol, ProtoOpts)

-> supervisor:child_spec()

Types:

• Ref = ref()
• NbAcceptors = non_neg_integer()
• Transport = module()
• TransOpts = any()
• Protocol = module()
• ProtoOpts = any()

Return child specifications for a new listener.

This function can be used to embed a listener directly in an application instead of letting Ranch handle it.

get_max_connections(Ref) -> MaxConns

Types:

• Ref = ref()
• MaxConns = max_conns()

Return the max number of connections allowed for the given listener.

get_port(Ref) -> Port

Types:

• Ref = ref()
• Port = inet:port_number()

Return the port for the given listener.

get_protocol_options(Ref) -> ProtoOpts

Types:

• Ref = ref()
• ProtoOpts = any()

Return the protocol options set for the given listener.

remove_connection(Ref) -> ok

Types:

• Ref = ref()

Do not count this connection when limiting the number of connections.

You can use this function for long-running connection processes which spend most of their time idling rather than consuming resources. This allows Ranch to accept a lot more connections without sacrificing the latency of the system.

This function may only be called from a connection process.

set_max_connections(Ref, MaxConns) -> ok

Types:

• Ref = ref()
• MaxConns = max_conns()

Set the max number of connections for the given listener.

The change will be applied immediately. If the new value is smaller than the previous one, Ranch will not kill the extra connections, but will wait for them to terminate properly.

set_protocol_options(Ref, ProtoOpts) -> ok

Types:

• Ref = ref()
• ProtoOpts = any()

Set the protocol options for the given listener.

The change will be applied immediately for all new connections. Old connections will not receive the new options.

start_listener(Ref, NbAcceptors, Transport, TransOpts, Protocol, ProtoOpts)

-> {ok, pid()} | {error, badarg}

Types:

• Ref = ref()
• NbAcceptors = non_neg_integer()
• Transport = module()
• TransOpts = any()
• Protocol = module()
• ProtoOpts = any()

Start listening for connections using the given transport and protocol. Returns the pid for this listener's supervisor.

There are five additional transport options that apply regardless of transport. They allow configuring how the connections are supervised, rate limited and allow using an already open listening socket.

The ack_timeout option defines how long post-accept socket initialization should take at a maximum. It defaults to 5000.

The connection_type option defines the type of process that will handle the connection. It can be either worker or supervisor. It defaults to worker.

The max_connections option determines how many active connections are allowed before Ranch starts throttling the accept rate. This is a soft limit. It defaults to 1024. Using the value infinity will disable this functionality entirely.

The shutdown option determines the policy used with regards to connection processes when shutting down the listener. It can be either a positive integer indicating the max number of ms the supervisor will wait before forcibly killing the children, or the atom brutal_kill. It defaults to 5000.

The socket option allow passing an already open listening socket. In this case, Ranch will not call Transport:listen/1 and so none of the transport specific options apply.

stop_listener(Ref) -> ok | {error, not_found}

Types:

• Ref = ref()

Stop the given listener.

The listener is stopped gracefully, first by closing the listening port, then by stopping the connection processes. These processes are stopped according to the shutdown transport option, which may be set to brutally kill all connection processes or give them some time to stop properly.

This function does not return until the listener is completely stopped.