[/
    Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)

    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

    Official repository: https://github.com/boostorg/beast
]

[/-----------------------------------------------------------------------------]

[section:timeouts Timeouts]

While
[link beast.ref.boost__beast__basic_stream `basic_stream`] and
[link beast.ref.boost__beast__basic_stream `tcp_stream`] support timeouts on
general logical operations, the websocket stream has a more sophisticated timeout
mechanism built-in which may be enabled and configured. The timeout features
of the TCP or basic stream should not be used when working with a websocket
stream. The interface to these timeout features is shown in this table.

[table WebSocket Timeout Interface
[[Name][Description]]
[[
    [link beast.ref.boost__beast__websocket__stream_base__timeout `stream_base::timeout`]
][
    This represents configured timeout settings for a websocket stream.
]]
[[
    [link beast.ref.boost__beast__websocket__stream_base__timeout.suggested `stream_base::timeout::suggested`]
][
    This function returns the suggested timeout settings for a given role
    (client or server).
]]
[[
    [link beast.ref.boost__beast__websocket__stream.set_option `stream::set_option`]
][
    This function sets timeout and other options on the stream.
]]
]

There are three timeout settings which may be set independently on the stream:

[table WebSocket Timeout Interface (2)
[[Name][Type][Description]]
[
    [[link beast.ref.boost__beast__websocket__stream_base__timeout.handshake_timeout `timeout::handshake_timeout`]]
    [`duration`]
    [
        This is the amount of time after which a handshake will time out.
        The handshake timeout applies to client handshakes, server handshakes,
        as well as the websocket closing handshake performed when either
        end of the connection wish to shut down.
        The value returned by
        [link beast.ref.boost__beast__websocket__stream_base.none `stream_base::none()`]
        may be assigned to disable this timeout.
    ]
][
    [[link beast.ref.boost__beast__websocket__stream_base__timeout.idle_timeout `timeout::idle_timeout`]]
    [`duration`]
    [
        If no data or control frames are received from the peer for a time
        equal to the idle timeout, then the connection will time out.
        The value returned by
        [link beast.ref.boost__beast__websocket__stream_base.none `stream_base::none()`]
        may be assigned to disable this timeout.
    ]
][
    [[link beast.ref.boost__beast__websocket__stream_base__timeout.keep_alive_pings `timeout::keep_alive_pings`]]
    [`bool`]
    [
        If the idle timeout is enabled, then the value of this setting
        controls whether or not a ping frame will be sent to the peer if
        no data is received for half of the idle timeout interval.
    ]
]
]

By default, timeouts on websocket streams are disabled. The easiest way
to turn them on is to set the suggested timeout settings on the stream.

[code_websocket_6_1]

For manual control over the settings, a timeout options object may be
constructed. Here we enable only the handshake timeout.

[code_websocket_6_2]

Timeout notifications are delivered to the caller by invoking the completion
handler for an outstanding asynchronous read operation with the error code
[link beast.ref.boost__beast__error `error::timeout`]. The implementation
will close the socket or stream before delivering this error. It is not
necessary to manually shut down the connection, as it will already be shut
down. A read operation must be outstanding for the error to be delivered.

[code_websocket_6_3]

[note
    Websocket timeout features are available only when using asynchronous I/O.
]

The timeouts on the websocket stream are incompatible with the timeouts
used in the `tcp_stream`. When constructing a websocket stream from a tcp
stream that has timeouts enabled, the timeout should be disabled first before
constructing the websocket stream, as shown.

[code_websocket_6_4]


[endsect]
