= ranch(3)

== Name

ranch - Socket acceptor pool

== Description

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

== Exports

Start/stop:

* link:man:ranch:start_listener(3)[ranch:start_listener(3)] - Start a listener
* link:man:ranch:stop_listener(3)[ranch:stop_listener(3)] - Stop a listener
* link:man:ranch:child_spec(3)[ranch:child_spec(3)] - Build child specifications for a new listener

Suspend/resume:

* link:man:ranch:suspend_listener(3)[ranch:suspend_listener(3)] - Suspend a running listener
* link:man:ranch:resume_listener(3)[ranch:resume_listener(3)] - Resume a suspended listener
* link:man:ranch:get_status(3)[ranch:get_status(3)] - Get a listener's running state

Connections:

* ranch:accept_ack(3) - Deprecated in favor of link:man:ranch:handshake(3)[ranch:handshake(3)]
* link:man:ranch:handshake(3)[ranch:handshake(3)] - Perform the transport handshake
* link:man:ranch:recv_proxy_header(3)[ranch:recv_proxy_header(3)] - Receive the PROXY protocol header
* link:man:ranch:remove_connection(3)[ranch:remove_connection(3)] - Remove connection from the count

Options:

* link:man:ranch:get_max_connections(3)[ranch:get_max_connections(3)] - Get the max number of connections per connection supervisor
* link:man:ranch:get_protocol_options(3)[ranch:get_protocol_options(3)] - Get the current protocol options
* link:man:ranch:get_transport_options(3)[ranch:get_transport_options(3)] - Get the current transport options
* link:man:ranch:set_max_connections(3)[ranch:set_max_connections(3)] - Set the max number of connections per connection supervisor
* link:man:ranch:set_protocol_options(3)[ranch:set_protocol_options(3)] - Set the protocol options
* link:man:ranch:set_transport_options(3)[ranch:set_transport_options(3)] - Set the transport options

Introspection:

* link:man:ranch:get_addr(3)[ranch:get_addr(3)] - Get the listening port and IP
* link:man:ranch:get_port(3)[ranch:get_port(3)] - Get the listening port
* link:man:ranch:info(3)[ranch:info(3)] - Overview of Ranch listeners
* link:man:ranch:procs(3)[ranch:procs(3)] - Retrieve pids from a listener
* link:man:ranch:wait_for_connections(3)[ranch:wait_for_connections(3)] - Wait for a specific number of connections

== Types

=== max_conns()

[source,erlang]
----
max_conns() = non_neg_integer() | infinity
----

Maximum number of connections allowed per connection supervisor.

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()

[source,erlang]
----
opt() = {ack_timeout, timeout()}
      | {connection_type, worker | supervisor}
      | {max_connections, max_conns()}
      | {num_acceptors, pos_integer()}
      | {shutdown, timeout() | brutal_kill}
----

Deprecated form for Ranch-specific options.

Please use the `opts()` type when you need to provide
Ranch-specific transport options. Socket options will
remain separate from the Ranch-specific options.

=== opts()

[source,erlang]
----
opts() = any() | #{
    connection_type   => worker | supervisor,
    handshake_timeout => timeout(),
    max_connections   => max_conns(),
    logger            => module(),
    num_acceptors     => pos_integer(),
    num_conns_sups    => pos_integer(),
    shutdown          => timeout() | brutal_kill,
    socket_opts       => any()
}
----

Transport options.

The transport options are a combination of Ranch-specific
options and socket options. Socket options may be given
directly (assuming they are not a map and no Ranch-specific
option needs to be given) or as part of `socket_opts`.

None of the options are required.

ack_timeout::

When `ack_timeout` is found in a transport options proplist,
it is converted to the `handshake_timeout` option from the
map. They are equivalent. The `ack_timeout` option will be
removed in Ranch 2.0.

connection_type (worker)::

Type of process that will handle the connection.

handshake_timeout (5000)::

Maximum allowed time for the `ranch:handshake/1,2` call to finish.

max_connections (1024)::

Maximum number of active connections per connection supervisor.
Soft limit. Use `infinity` to disable the limit entirely.

num_acceptors (10)::

Number of processes that accept connections.

num_conns_sups - see below::

Number of processes that supervise connection processes.
If not specified, defaults to be equal to `num_acceptors`.

shutdown (5000)::

Maximum allowed time for children to stop on listener shutdown.

socket_opts::

Socket options given to `Transport:listen/1`. Please refer to the
documentation of the transport module you are using for more details.

=== ref()

[source,erlang]
----
ref() = any()
----

Unique name used to refer to a listener.

== Changelog

* *2.0*: The option `max_connections` is now per connection supervisor.
* *2.0*: The `num_conns_sup` option was added.
* *2.0*: The `socket` option was removed.
* *1.6*: The `logger` option was added.
* *1.6*: The `opt()` type was deprecated in favor of the new `opts()` type.

== See also

link:man:ranch(7)[ranch(7)]
