Struct AsyncZstdSeekableReader 

pub struct AsyncZstdSeekableReader<'dict, R> { /* private fields */ }

A wrapper around AsyncZstdReader with extra support for seeking. Created via the method AsyncZstdReader::seekable.

The underlying reader R should implement the following traits:

• tokio
  • tokio::io::AsyncBufRead + tokio::io::AsyncSeek (required for tokio::io::AsyncRead, tokio::io::AsyncBufRead, and tokio::io::AsyncSeek impls)
• futures
  • futures::AsyncBufRead + futures::AsyncSeek (required for futures::AsyncRead, futures::AsyncBufRead, and tokio::io::AsyncSeek impls)

By default, seeking within the stream will linearly decompress until reaching the target!

Seeking can do a lot better when the underlying stream is broken up into multiple frames, such as a stream that uses the zstd seekable format. You can create such a stream using ZstdWriterBuilder::with_seek_table.

There are two situations where seeking can take advantage of a seek table:

1. When a seek table is provided up-front using ZstdReaderBuilder::with_seek_table. See crate::table::read_seek_table for reading a seek table from a reader (there are also async-friendly functions available).
2. When rewinding to a previously-decompressed frame. Frame offsets are automatically recorded during decompression.

Even if a seek table is used, seeking will still need to rewind to the start of a frame, then decompress until reaching the target offset.

Trait Implementations

impl<R> AsyncBufRead for AsyncZstdSeekableReader<'_, R>

where R: AsyncBufRead + AsyncSeek,

fn poll_fill_buf( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<&[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<R> AsyncBufRead for AsyncZstdSeekableReader<'_, R>

where R: AsyncBufRead + AsyncSeek,

fn poll_fill_buf( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<&[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<R> AsyncRead for AsyncZstdSeekableReader<'_, R>

where R: AsyncBufRead + AsyncSeek,

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

Attempts to read from the AsyncRead into buf.

impl<R> AsyncRead for AsyncZstdSeekableReader<'_, R>

where R: AsyncBufRead + AsyncSeek,

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<R> AsyncSeek for AsyncZstdSeekableReader<'_, R>

where R: AsyncBufRead + AsyncSeek,

fn start_seek(self: Pin<&mut Self>, position: SeekFrom) -> Result<()>

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

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

Waits for a seek operation to complete.

impl<R> AsyncSeek for AsyncZstdSeekableReader<'_, R>

where R: AsyncBufRead + AsyncSeek,

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

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

impl<'__pin, 'dict, R> Unpin for AsyncZstdSeekableReader<'dict, R>

where PinnedFieldsOf<__Origin<'__pin, 'dict, R>>: Unpin,