boost::corosio::native_stream_file

Reads and writes a file sequentially, calling the backend directly.

Synopsis

Declared in <boost/corosio/native/native_stream_file.hpp>

template<auto Backend>
class native_stream_file
    : public stream_file

Description

This class template inherits from stream_file. It shadows read_some / write_some with versions that call the backend implementation directly. The compiler can then inline through the entire call chain.

Non‐async operations (open, close, size, resize, seek, sync_data, sync_all) remain unchanged and dispatch through the compiled library.

A native_stream_file IS‐A stream_file and can be passed to any function expecting stream_file& or io_stream&, in which case virtual dispatch is used transparently.

On POSIX platforms, file I/O is dispatched to a thread pool regardless of the chosen reactor backend. All three reactor tags (epoll, select, kqueue) therefore resolve to the same underlying implementation. The Backend template parameter exists for API symmetry with native_tcp_socket and friends. The vtable savings are smaller relative to the thread‐pool / overlapped‐I/O cost than they are for socket operations.

Thread Safety

Same as stream_file.

Example

capy::task<>
open_and_read()
{
    corosio::native_io_context<corosio::epoll> ctx;
    corosio::native_stream_file<corosio::epoll> f(ctx);
    if (auto ec = f.open("data.bin", corosio::file_base::read_only))
        co_return;

    char buf[4096];
    auto [ec, n] = co_await f.read_some(capy::mutable_buffer(buf, sizeof(buf)));
    if (ec)
        co_return;
}