Struct BufReader

pub struct BufReader<'buf, R> { /* private fields */ }

Available on crate feature io only.

The BufReader struct adds buffering to any reader.

It can be excessively inefficient to work directly with a AsyncRead instance. A BufReader performs large, infrequent reads on the underlying AsyncRead and maintains an in-memory buffer of the results.

BufReader can improve the speed of programs that make small and repeated read calls to the same file or network socket. It does not help when reading very large amounts at once, or reading just one or a few times. It also provides no advantage when reading from a source that is already in memory, like a Vec<u8>.

When the BufReader is dropped, the contents of its buffer will be discarded. Creating multiple instances of a BufReader on the same stream can cause data loss.

Implementations

impl<'buf, R: AsyncRead> BufReader<'buf, R>

pub fn new(buf: &'buf mut [u8], inner: R) -> Self

Creates a new BufReader with the specified buffer capacity.

pub fn get_ref(&self) -> &R

Gets a reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

pub fn get_mut(&mut self) -> &mut R

Gets a mutable reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R>

Gets a pinned mutable reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

pub fn into_inner(self) -> R

Consumes this BufReader, returning the underlying reader.

Note that any leftover data in the internal buffer is lost.

pub fn buffer(&self) -> &[u8]

Returns a reference to the internally buffered data.

Unlike fill_buf, this will not attempt to fill the buffer if it is empty.

Trait Implementations

impl<R: AsyncRead> AsyncBufRead for BufReader<'_, R>

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

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: AsyncRead> AsyncRead for BufReader<'_, R>

type Error = <R as AsyncRead>::Error

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

Attempt to read from the AsyncRead into buf. On success, returns Poll::Ready(Ok(num_bytes_read)). If no data is available for reading, this method returns Poll::Pending and arranges for the current task to be woken.

fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>

where Self: Unpin,

Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type.

impl<'__pin, 'buf, R> Unpin for BufReader<'buf, R>

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