Struct `BufWriter`

struct BufWriter<W> { ... }

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: AsyncWrite> BufWriter<W>`

fn new(inner: W) -> Self

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

fn with_capacity(cap: usize, inner: W) -> Self

Creates a new BufWriter with the specified buffer capacity.

fn get_ref(self: &Self) -> &W

Gets a reference to the underlying writer.

fn get_mut(self: &mut Self) -> &mut W

Gets a mutable reference to the underlying writer.

It is inadvisable to directly write to the underlying writer.

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

Gets a pinned mutable reference to the underlying writer.

It is inadvisable to directly write to the underlying writer.

fn into_inner(self: Self) -> W

Consumes this BufWriter, returning the underlying writer.

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

fn buffer(self: &Self) -> &[u8]

Returns a reference to the internally buffered data.

`impl<'__pin, W> Unpin for BufWriter<W>`

`impl<R> AsyncBufReadExt for BufWriter<W>`

`impl<R> AsyncReadExt for BufWriter<W>`

`impl<S> AsyncSeekExt for BufWriter<W>`

`impl<T> Any for BufWriter<W>`

fn type_id(self: &Self) -> TypeId

`impl<T> Borrow for BufWriter<W>`

fn borrow(self: &Self) -> &T

`impl<T> BorrowMut for BufWriter<W>`

fn borrow_mut(self: &mut Self) -> &mut T

`impl<T> From for BufWriter<W>`

fn from(t: T) -> T: Returns the argument unchanged.

`impl<T, U> Into for BufWriter<W>`

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

`impl<T, U> TryFrom for BufWriter<W>`

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

`impl<T, U> TryInto for BufWriter<W>`

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>

`impl<W> AsyncWriteExt for BufWriter<W>`

`impl<W> Freeze for BufWriter<W>`

`impl<W> RefUnwindSafe for BufWriter<W>`

`impl<W> Send for BufWriter<W>`

`impl<W> Sync for BufWriter<W>`

`impl<W> UnsafeUnpin for BufWriter<W>`

`impl<W> UnwindSafe for BufWriter<W>`

`impl<W: AsyncWrite + AsyncBufRead> AsyncBufRead for BufWriter<W>`

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

`impl<W: AsyncWrite + AsyncRead> AsyncRead for BufWriter<W>`

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

`impl<W: AsyncWrite + AsyncSeek> AsyncSeek for BufWriter<W>`

fn start_seek(self: Pin<&mut Self>, pos: SeekFrom) -> Result<()>
fn poll_complete(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<u64>>

`impl<W: AsyncWrite> AsyncWrite for BufWriter<W>`

fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize>>
fn poll_write_vectored(self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>]) -> Poll<Result<usize>>
fn is_write_vectored(self: &Self) -> bool
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

`impl<W: fmt::Debug> Debug for BufWriter<W>`

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