Trait opendal::raw::oio::Read

pub trait Read: Unpin + Send + Sync {
    // Required methods
    fn poll_read(
        &mut self,
        cx: &mut Context<'_>,
        buf: &mut [u8]
    ) -> Poll<Result<usize>>;
    fn poll_seek(
        &mut self,
        cx: &mut Context<'_>,
        pos: SeekFrom
    ) -> Poll<Result<u64>>;
    fn poll_next(&mut self, cx: &mut Context<'_>) -> Poll<Option<Result<Bytes>>>;
}

Read is the trait that OpenDAL returns to callers.

Read is compose of the following trait

• AsyncRead
• AsyncSeek
• Stream<Item = Result<Bytes>>

AsyncRead is required to be implemented, AsyncSeek and Stream is optional. We use Read to make users life easier.

Required Methods

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

Read bytes asynchronously.

fn poll_seek(&mut self, cx: &mut Context<'_>, pos: SeekFrom) -> Poll<Result<u64>>

Seek asynchronously.

Returns Unsupported error if underlying reader doesn’t support seek.

fn poll_next(&mut self, cx: &mut Context<'_>) -> Poll<Option<Result<Bytes>>>

Stream Bytes from underlying reader.

Returns Unsupported error if underlying reader doesn’t support stream.

This API exists for avoiding bytes copying inside async runtime. Users can poll bytes from underlying reader and decide when to read/consume them.

Trait Implementations

impl AsyncRead for dyn Read

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 AsyncSeek for dyn Read

fn poll_seek( self: Pin<&mut Self>, cx: &mut Context<'_>, pos: SeekFrom ) -> Poll<Result<u64>>

Attempt to seek to an offset, in bytes, in a stream.

impl Stream for dyn Read

type Item = Result<Bytes, Error>

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_> ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.

Implementations on Foreign Types

impl Read for ()

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

fn poll_seek(&mut self, cx: &mut Context<'_>, pos: SeekFrom) -> Poll<Result<u64>>

fn poll_next(&mut self, cx: &mut Context<'_>) -> Poll<Option<Result<Bytes>>>

impl<T: Read + ?Sized> Read for Box<T>

Box<dyn Read> won’t implement Read automatically. To make Reader work as expected, we must add this impl.

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

fn poll_seek(&mut self, cx: &mut Context<'_>, pos: SeekFrom) -> Poll<Result<u64>>

fn poll_next(&mut self, cx: &mut Context<'_>) -> Poll<Option<Result<Bytes>>>

Implementors

impl Read for Reader

impl Read for IncomingAsyncBody

impl Read for Cursor

impl<A: Accessor> Read for RangeReader<A>

impl<R> Read for FdReader<R>where R: AsyncRead + AsyncSeek + Unpin + Send + Sync,

impl<R: Read> Read for IntoStreamableReader<R>