Boost C++ Libraries

A Stream with attached DynamicBuffer to buffer reads.

Synopsis

Defined in header <boost/beast/core/buffered_read_stream.hpp>

template<
    class Stream,
    class DynamicBuffer>
class buffered_read_stream

Types

Member Functions

Description

This wraps a Stream implementation so that calls to write are passed through to the underlying stream, while calls to read will first consume the input sequence stored in a DynamicBuffer which is part of the object.

The use-case for this class is different than that of the net::buffered_read_stream. It is designed to facilitate the use of net::read_until, and to allow buffers acquired during detection of handshakes to be made transparently available to callers. A hypothetical implementation of the buffered version of net::ssl::stream::async_handshake could make use of this wrapper.

Uses:

Example:

// Process the next HTTP header on the stream,
// leaving excess bytes behind for the next call.
//
template < class Stream, class DynamicBuffer>
void process_http_message(
    buffered_read_stream<Stream, DynamicBuffer>& stream)
{
    // Read up to and including the end of the HTTP
    // header, leaving the sequence in the stream's
    // buffer. read_until may read past the end of the
    // headers; the return value will include only the
    // part up to the end of the delimiter.
    //
    std::size_t bytes_transferred =
        net::read_until(
            stream.next_layer(), stream.buffer(), "\r\n\r\n" );

    // Use buffers_prefix() to limit the input
    // sequence to only the data up to and including
    // the trailing "\r\n\r\n".
    //
    auto header_buffers = buffers_prefix(
        bytes_transferred, stream.buffer().data());

    ...

    // Discard the portion of the input corresponding
    // to the HTTP headers.
    //
    stream.buffer().consume(bytes_transferred);

    // Everything we read from the stream
    // is part of the content-body.
}

Template Parameters