Struct BufReader

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

Wraps a reader and buffers input from AsyncRead

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

BufReader<R> 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<R> is dropped, the contents of its buffer will be discarded. Reading from the underlying reader after unwrapping the BufReader<R> with BufReader::into_inner can cause data loss.

Caution

Due to the pass-by-ownership nature of completion-based IO, the buffer is passed to the inner reader when fill_buf is called. If the future returned by fill_buf is dropped before inner read is completed, BufReader will not be able to retrieve the buffer, causing panic on next fill_buf call.

Implementations

impl<R> BufReader<R>

pub fn new(reader: R) -> Self

Creates a new BufReader with a default buffer capacity. The default is currently 8 KB, but may change in the future.

pub fn with_capacity(cap: usize, reader: R) -> Self

Creates a new BufReader with the specified buffer capacity.

Trait Implementations

impl<R: AsyncRead> AsyncBufRead for BufReader<R>

async fn fill_buf(&mut self) -> Result<&[u8]>

Try fill the internal buffer with data

fn consume(&mut self, amount: usize)

Mark how much data is read

impl<R: AsyncRead> AsyncRead for BufReader<R>

async fn read<B: IoBufMut>(&mut self, buf: B) -> BufResult<usize, B>

Read some bytes from this source into the IoBufMut buffer and return a BufResult, consisting of the buffer and a usize indicating how many bytes were read.

async fn read_vectored<V: IoVectoredBufMut>( &mut self, buf: V, ) -> BufResult<usize, V>

Like read, except that it reads into a type implements IoVectoredBufMut.

impl<R: Debug> Debug for BufReader<R>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<R> IntoInner for BufReader<R>

type Inner = R

The inner type.

fn into_inner(self) -> Self::Inner

Get the inner buffer.