Struct BytesCursor 

pub struct BytesCursor { /* private fields */ }

A cursor over raw bytes of the response returned by Query::fetch_bytes.

Unlike RowCursor which emits rows deserialized as structures from RowBinary, this cursor emits raw bytes without deserialization.

Integration

Additionally to BytesCursor::next and BytesCursor::collect, this cursor implements:

• AsyncRead and AsyncBufRead for tokio-based ecosystem.
• futures_util::Stream, futures_util::AsyncRead and futures_util::AsyncBufRead for futures-based ecosystem. (requires the futures03 feature)

For instance, if the requested format emits each row on a newline (e.g. JSONEachRow, CSV, TSV, etc.), the cursor can be read line by line using AsyncBufReadExt::lines. Note that this method produces a new String for each line, so it’s not the most performant way to iterate.

Note: methods of these traits use std::io::Error for errors. To get an original error from this crate, use From conversion.

Implementations

impl BytesCursor

pub async fn next(&mut self) -> Result<Option<Bytes>>

Emits the next bytes chunk.

Cancel safety

This method is cancellation safe.

pub async fn collect(&mut self) -> Result<Bytes>

Collects the whole response into a single Bytes.

Cancel safety

This method is NOT cancellation safe. If cancelled, already collected bytes are lost.

pub fn received_bytes(&self) -> u64

Returns the total size in bytes received from the CH server since the cursor was created.

This method counts only size without HTTP headers for now. It can be changed in the future without notice.

pub fn decoded_bytes(&self) -> u64

Returns the total size in bytes decompressed since the cursor was created.

Trait Implementations

impl AsyncBufRead for BytesCursor

fn poll_fill_buf( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<IoResult<&[u8]>>

Attempts to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(self: Pin<&mut Self>, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read.

impl AsyncBufRead for BytesCursor

Available on crate feature futures03 only.

fn poll_fill_buf( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<IoResult<&[u8]>>

Attempt to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(self: Pin<&mut Self>, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read.

impl AsyncRead for BytesCursor

fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>, ) -> Poll<IoResult<()>>

Attempts to read from the AsyncRead into buf.

impl AsyncRead for BytesCursor

Available on crate feature futures03 only.

fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<IoResult<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 FusedStream for BytesCursor

Available on crate feature futures03 only.

fn is_terminated(&self) -> bool

Returns true if the stream should no longer be polled.

impl Stream for BytesCursor

Available on crate feature futures03 only.

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.