[−][src]Struct futures::io::BufWriter
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.
Methods
impl<W> BufWriter<W> where
W: AsyncWrite,
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W: AsyncWrite,
pub fn new(inner: W) -> BufWriter<W>
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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>
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Creates a new BufWriter
with the specified buffer capacity.
ⓘImportant traits for &'_ mut Fpub fn get_ref(&self) -> &W
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Gets a reference to the underlying writer.
ⓘImportant traits for &'_ mut Fpub fn get_mut(&mut self) -> &mut W
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Gets a mutable reference to the underlying writer.
It is inadvisable to directly write to the underlying writer.
ⓘImportant traits for Pin<P>pub fn get_pin_mut(self: Pin<&mut BufWriter<W>>) -> Pin<&mut W>
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Gets a pinned mutable reference to the underlying writer.
It is inadvisable to directly write to the underlying writer.
pub fn into_inner(self) -> W
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Consumes this BufWriter
, returning the underlying writer.
Note that any leftover data in the internal buffer is lost.
pub fn buffer(&self) -> &[u8]
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Returns a reference to the internally buffered data.
Trait Implementations
impl<W> AsyncSeek for BufWriter<W> where
W: AsyncWrite + AsyncSeek,
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W: AsyncWrite + AsyncSeek,
fn poll_seek(
self: Pin<&mut BufWriter<W>>,
cx: &mut Context,
pos: SeekFrom
) -> Poll<Result<u64, Error>>
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self: Pin<&mut BufWriter<W>>,
cx: &mut Context,
pos: SeekFrom
) -> Poll<Result<u64, Error>>
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,
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W: AsyncWrite,
fn poll_write(
self: Pin<&mut BufWriter<W>>,
cx: &mut Context,
buf: &[u8]
) -> Poll<Result<usize, Error>>
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self: Pin<&mut BufWriter<W>>,
cx: &mut Context,
buf: &[u8]
) -> Poll<Result<usize, Error>>
fn poll_write_vectored(
self: Pin<&mut BufWriter<W>>,
cx: &mut Context,
bufs: &[IoSlice]
) -> Poll<Result<usize, Error>>
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self: Pin<&mut BufWriter<W>>,
cx: &mut Context,
bufs: &[IoSlice]
) -> Poll<Result<usize, Error>>
fn poll_flush(
self: Pin<&mut BufWriter<W>>,
cx: &mut Context
) -> Poll<Result<(), Error>>
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self: Pin<&mut BufWriter<W>>,
cx: &mut Context
) -> Poll<Result<(), Error>>
fn poll_close(
self: Pin<&mut BufWriter<W>>,
cx: &mut Context
) -> Poll<Result<(), Error>>
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self: Pin<&mut BufWriter<W>>,
cx: &mut Context
) -> Poll<Result<(), Error>>
impl<W> Debug for BufWriter<W> where
W: Debug + AsyncWrite,
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W: Debug + AsyncWrite,
Auto Trait Implementations
impl<W> Send for BufWriter<W> where
W: Send,
W: Send,
impl<W> Unpin for BufWriter<W> where
W: Unpin,
W: Unpin,
impl<W> Sync for BufWriter<W> where
W: Sync,
W: Sync,
impl<W> UnwindSafe for BufWriter<W> where
W: UnwindSafe,
W: UnwindSafe,
impl<W> RefUnwindSafe for BufWriter<W> where
W: RefUnwindSafe,
W: RefUnwindSafe,
Blanket Implementations
impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> From<T> for T
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
ⓘImportant traits for &'_ mut Ffn borrow_mut(&mut self) -> &mut T
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
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W: AsyncWrite + ?Sized,
ⓘImportant traits for Flush<'_, W>fn flush(&mut self) -> Flush<Self> where
Self: Unpin,
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Self: Unpin,
ⓘImportant traits for Close<'_, W>fn close(&mut self) -> Close<Self> where
Self: Unpin,
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Self: Unpin,
ⓘImportant traits for Write<'_, W>fn write(&'a mut self, buf: &'a [u8]) -> Write<'a, Self> where
Self: Unpin,
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Self: Unpin,
ⓘImportant traits for WriteVectored<'_, W>fn write_vectored(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectored<'a, Self> where
Self: Unpin,
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&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectored<'a, Self> where
Self: Unpin,
ⓘImportant traits for WriteAll<'_, W>fn write_all(&'a mut self, buf: &'a [u8]) -> WriteAll<'a, Self> where
Self: Unpin,
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Self: Unpin,
ⓘImportant traits for Compat<R>fn compat_write(self) -> Compat<Self> where
Self: Unpin,
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Self: Unpin,
fn into_sink<Item>(self) -> IntoSink<Self, Item> where
Item: AsRef<[u8]>,
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Item: AsRef<[u8]>,
impl<S> AsyncSeekExt for S where
S: AsyncSeek + ?Sized,
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S: AsyncSeek + ?Sized,