Trait tokio::io::AsyncSeek

pub trait AsyncSeek {
    fn start_seek(self: Pin<&mut Self>, position: SeekFrom) -> Result<()>;
    fn poll_complete(
        self: Pin<&mut Self>, 
        cx: &mut Context<'_>
    ) -> Poll<Result<u64>>;
}

Seek bytes asynchronously.

This trait is analogous to the std::io::Seek trait, but integrates with the asynchronous task system. In particular, the start_seek method, unlike Seek::seek, will not block the calling thread.

Utilities for working with AsyncSeek values are provided by AsyncSeekExt.

Required methods

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

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

A seek beyond the end of a stream is allowed, but behavior is defined by the implementation.

If this function returns successfully, then the job has been submitted. To find out when it completes, call poll_complete.

Errors

This function can return io::ErrorKind::Other in case there is another seek in progress. To avoid this, it is advisable that any call to start_seek is preceded by a call to poll_complete to ensure all pending seeks have completed.

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

Waits for a seek operation to complete.

If the seek operation completed successfully, this method returns the new position from the start of the stream. That position can be used later with SeekFrom::Start. Repeatedly calling this function without calling start_seek might return the same result.

Errors

Seeking to a negative offset is considered an error.

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Implementations on Foreign Types

impl<T: ?Sized + AsyncSeek + Unpin> AsyncSeek for Box<T>

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

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

impl<T: ?Sized + AsyncSeek + Unpin> AsyncSeek for &mut T

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

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

impl<P> AsyncSeek for Pin<P> where
    P: DerefMut + Unpin,
    P::Target: AsyncSeek, 

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

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

impl<T: AsRef<[u8]> + Unpin> AsyncSeek for Cursor<T>

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

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

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Implementors

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