Struct LimitReader

pub struct LimitReader<T>
where
    T: AsyncRead + Unpin,
{ /* private fields */ }

Pure implementation for LimitReader to restrict number of bytes can be read Useful when you want to read stream but want to end early no matter what

E.g. you can’t accept more than 20MiB as HTTP Post body, you can limit it here Example:

async fn do_test() -> Result<(), Box<dyn std::error::Error>> {
    use tokio::io::{AsyncReadExt};
    let mut f = tokio::fs::File::open("input.txt").await?;
    let mut reader = crate::asyncio_utils::LimitReader::new(f, Some(18)); // only read at most 18 bytes
 
    let mut buf = vec![0u8; 2096];
    reader.read(&mut buf).await?;
    return Ok(());
}

Implementations

impl<T> LimitReader<T>

where T: AsyncRead + Unpin,

Implementation of AysncRead for LimitReader

pub fn new(src: T, limit: Option<usize>) -> LimitReader<T>

Create new LimitReader from another AsyncRead (typically File or Stream)

Argument src is the underlying reader limit is the byte limit. Node that the limit can be Some(limit) -> The limit is set None -> No limit (std::usize::MAX)

pub fn destruct(self) -> (usize, T)

Destruct the LimitReader and get the total read bytes and the original reader

Takes the ownership and You can’t use the LimitReader after this call

Trait Implementations

impl<T> AsyncRead for LimitReader<T>

where T: AsyncRead + Unpin,

Implementation of AsyncRead

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

Attempts to read from the AsyncRead into buf.