Struct futures::io::BufWriter[][src]

pub struct BufWriter<W> { /* fields omitted */ }

Wraps a writer and buffers its output.

It can be excessively inefficient to work directly with something that implements AsyncWrite. A BufWriter keeps an in-memory buffer of data and writes it to an underlying writer in large, infrequent batches.

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

When the BufWriter is dropped, the contents of its buffer will be discarded. Creating multiple instances of a BufWriter on the same stream can cause data loss. If you need to write out the contents of its buffer, you must manually call flush before the writer is dropped.

Implementations

impl<W> BufWriter<W> where
    W: AsyncWrite
[src]

pub fn new(inner: W) -> BufWriter<W>[src]

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

pub fn with_capacity(cap: usize, inner: W) -> BufWriter<W>[src]

Creates a new BufWriter with the specified buffer capacity.

pub fn get_ref(&self) -> &W

Notable traits for &'_ mut F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;
[src]

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

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

Notable traits for &'_ mut F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;
[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 BufWriter<W>>) -> Pin<&mut W>

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) -> W[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]

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
[src]

Returns a reference to the internally buffered data.

Trait Implementations

impl<W> AsyncBufRead for BufWriter<W> where
    W: AsyncBufRead
[src]

impl<W> AsyncRead for BufWriter<W> where
    W: AsyncRead
[src]

impl<W> AsyncSeek for BufWriter<W> where
    W: AsyncWrite + AsyncSeek
[src]

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

Seek to the offset, in bytes, in the underlying writer.

Seeking always writes out the internal buffer before seeking.

impl<W> AsyncWrite for BufWriter<W> where
    W: AsyncWrite
[src]

impl<W> Debug for BufWriter<W> where
    W: Debug
[src]

impl<'__pin, W> Unpin for BufWriter<W> where
    __Origin<'__pin, W>: Unpin
[src]

Auto Trait Implementations

impl<W> RefUnwindSafe for BufWriter<W> where
    W: RefUnwindSafe

impl<W> Send for BufWriter<W> where
    W: Send

impl<W> Sync for BufWriter<W> where
    W: Sync

impl<W> UnwindSafe for BufWriter<W> where
    W: 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.