Struct fuchsia_fs::file::AsyncReader

pub struct AsyncReader { /* private fields */ }

Wraps a fidl_fuchsia_io::FileProxy and implements futures::io::AsyncRead, which allows one to perform asynchronous file reads that don’t block the current thread while waiting for data.

Implementations

impl AsyncReader

pub fn from_proxy(file: FileProxy) -> Result<Self, AsyncReaderError>

Errors if the provided FileProxy does not exclusively own the wrapped channel.

Exclusive ownership avoids surprising behavior arising from the mismatch between the semantics for AsyncRead and fuchsia.io/File.Read. On e.g. Linux, if two AsyncRead objects were wrapping the same file descriptor and a call to poll_read on one of the AsyncRead objects returned Pending, a client would generally not expect the offset of the underlying file descriptor to advance. Meaning that a client could then call poll_read on the other AsyncRead object and expect not to miss any file contents. However, with an AsyncRead implementation that wraps fuchsia.io/File.Read, a poll_read call that returns Pending would advance the file offset, meaning that interleaving usage of AsyncRead objects that share a channel would return file contents in surprising order.

Trait Implementations

impl AsyncRead for AsyncReader

fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize>>

Attempt to read from the AsyncRead into buf.

fn poll_read_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &mut [IoSliceMut<'_>], ) -> Poll<Result<usize, Error>>

Attempt to read from the AsyncRead into bufs using vectored IO operations.

impl Debug for AsyncReader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.