Struct futures_util::io::BufReader[][src]

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

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<R: AsyncRead> BufReader<R>[src]

pub fn new(inner: R) -> Self[src]

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(capacity: usize, inner: R) -> Self[src]

Creates a new BufReader with the specified buffer capacity.

pub fn get_ref(&self) -> &R[src]

Acquires a reference to the underlying sink or stream that this combinator is pulling from.

pub fn get_mut(&mut self) -> &mut R[src]

Acquires a mutable reference to the underlying sink or stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.

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

Notable traits for Pin<P>

impl<P> Future for Pin<P> where
    P: Unpin + DerefMut,
    <P as Deref>::Target: Future
type Output = <<P as Deref>::Target as Future>::Output;
[src]

Acquires a pinned mutable reference to the underlying sink or stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.

pub fn into_inner(self) -> R[src]

Consumes this combinator, returning the underlying sink or stream.

Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.

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

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>[src]

impl<R: AsyncRead> AsyncRead for BufReader<R>[src]

impl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R>[src]

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

Seek to an offset, in bytes, in the underlying reader.

The position used for seeking with SeekFrom::Current(_) is the position the underlying reader would be at if the BufReader had no internal buffer.

Seeking always discards the internal buffer, even if the seek position would otherwise fall within it. This guarantees that calling .into_inner() immediately after a seek yields the underlying reader at the same position.

See AsyncSeek for more details.

Note: In the edge case where you’re seeking with SeekFrom::Current(n) where n minus the internal buffer length overflows an i64, two seeks will be performed instead of one. If the second seek returns Err, the underlying reader will be left at the same position it would have if you called seek with SeekFrom::Current(0).

impl<R: AsyncWrite> AsyncWrite for BufReader<R>[src]

impl<R: Debug> Debug for BufReader<R>[src]

impl<'__pin, R> Unpin for BufReader<R> where
    __Origin<'__pin, R>: Unpin
[src]

Auto Trait Implementations

impl<R> RefUnwindSafe for BufReader<R> where
    R: RefUnwindSafe

impl<R> Send for BufReader<R> where
    R: Send

impl<R> Sync for BufReader<R> where
    R: Sync

impl<R> UnwindSafe for BufReader<R> where
    R: UnwindSafe

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<R> AsyncBufReadExt for R where
    R: AsyncBufRead + ?Sized
[src]

impl<R> AsyncReadExt for R where
    R: AsyncRead + ?Sized
[src]

impl<S> AsyncSeekExt for S where
    S: AsyncSeek + ?Sized
[src]

impl<W> AsyncWriteExt for W where
    W: AsyncWrite + ?Sized
[src]

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.