flat_stream

Stream wrapper to improve ssl::stream write performance.

Synopsis

Defined in header <boost/beast/experimental/core/flat_stream.hpp>

template<
    class NextLayer>
class flat_stream

Types

Name	Description
executor_type	The type of the executor associated with the object.
lowest_layer_type	The type of the lowest layer.
next_layer_type	The type of the next layer.

Member Functions

Name	Description
async_read_some	Start an asynchronous read.
async_write_some	Start an asynchronous write.
flat_stream	Constructor.
get_executor	Get the executor associated with the object.
lowest_layer	Get a reference to the lowest layer.
next_layer	Get a reference to the next layer.
operator=
read_some	Read some data from the stream.
write_some	Write some data to the stream.
~flat_stream	Destructor.

This wrapper flattens writes for buffer sequences having length greater than 1 and total size below a predefined amount, using a dynamic memory allocation. It is primarily designed to overcome a performance limitation of the current version of boost::asio::ssl::stream, which does not use OpenSSL's scatter/gather interface for its low-level read some and write some operations.

Example

To use the flat_stream template with SSL streams, declare a variable of the correct type. Parameters passed to the constructor will be forwarded to the next layer's constructor:

flat_stream<ssl::stream<ip::tcp::socket>> fs{ioc, ctx};

Alternatively you can write

ssl::stream<ip::tcp::socket> ss{ioc, ctx};
flat_stream<ssl::stream<ip::tcp::socket>&> fs{ss};

The resulting stream may be passed to any stream algorithms which operate on synchronous or asynchronous read or write streams, examples include:

boost::asio::read, boost::asio::async_read
boost::asio::write, boost::asio::async_write
boost::asio::read_until, boost::asio::async_read_until

The stream may also be used as a template parameter in other stream wrappers, such as for websocket:

websocket::stream<flat_stream<ssl::stream<ip::tcp::socket>>> ws{ioc, ctx};

Template Parameters

Type	Description
`NextLayer`	The type representing the next layer, to which data will be read and written during operations. For synchronous operations, the type must support the SyncStream concept. For asynchronous operations, the type must support the AsyncStream concept. This type will usually be some variation of `boost::asio::ssl::stream`.

Concepts

AsyncStream SyncStream

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