boost::corosio::native_stream_file

A sequential file with devirtualized async I/O operations.

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 and shadows read_some / write_some with versions that call the backend implementation directly, allowing the compiler to 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, so all three reactor tags (epoll, select, kqueue) 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

#include <boost/corosio/native/native_stream_file.hpp>

native_io_context<epoll> ctx;
native_stream_file<epoll> f(ctx);
f.open("data.bin", file_base::read_only);
char buf[4096];
auto [ec, n] = co_await f.read_some(
    capy::mutable_buffer(buf, sizeof(buf)));

Base Classes

Name Description

An asynchronous sequential file for coroutine I/O.

Types

Name

Description

RAII wrapper for I/O object implementation lifetime.

implementation

Platform‐specific file implementation interface.

Service interface for I/O object lifecycle management.

Member Functions

Name

Description

native_stream_file [constructor] [deleted]

Constructors

operator= [deleted]

Assignment operators

Adopt an existing native handle.

Cancel pending asynchronous operations.

Close the file.

Return the execution context.

Check if the file is open.

native_handle

Get the native file descriptor or handle.

Open a file.

Asynchronously read data from the file.

Release ownership of the native handle.

Resize the file to new_size bytes.

Move the file position.

Return the file size in bytes.

Synchronize file data and metadata to stable storage.

Synchronize file data to stable storage.

Asynchronously write data to the file.

Protected Types

Name

Description

read_some_awaitable

Awaitable for async read operations.

write_some_awaitable

Awaitable for async write operations.

Protected Member Functions

Name

Description

operator= [deleted]

Move assign from another I/O object.

do_read_some [virtual]

do_read_some overloads

do_write_some [virtual]

do_write_some overloads

Protected Static Member Functions

Name

Description

create_handle

Create a handle bound to a service found in the context.

Protected Data Members

Name

Description

The platform I/O handle owned by this object.

Template Parameters

Name Description

Backend

A backend tag value (e.g., epoll, iocp).

See Also

stream_file, epoll_t, iocp_t

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