Struct tokio::io::BufWriter

source ·
pub struct BufWriter<W> { /* private fields */ }
Expand description

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§

source§

impl<W: AsyncWrite> BufWriter<W>

source

pub 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.

source

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

Creates a new BufWriter with the specified buffer capacity.

source

pub fn get_ref(&self) -> &W

Gets a reference to the underlying writer.

source

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

Gets a mutable reference to the underlying writer.

It is inadvisable to directly write to the underlying writer.

source

pub 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.

source

pub fn into_inner(self) -> W

Consumes this BufWriter, returning the underlying writer.

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

source

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

Returns a reference to the internally buffered data.

Trait Implementations§

source§

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

source§

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

Attempts to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
source§

fn consume(self: Pin<&mut Self>, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read. Read more
source§

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

source§

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

Attempts to read from the AsyncRead into buf. Read more
source§

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

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

Seeking always writes out the internal buffer before seeking.

source§

fn start_seek(self: Pin<&mut Self>, pos: SeekFrom) -> Result<()>

Attempts to seek to an offset, in bytes, in a stream. Read more
source§

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

Waits for a seek operation to complete. Read more
source§

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

source§

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

Attempt to write bytes from buf into the object. Read more
source§

fn poll_write_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>] ) -> Poll<Result<usize>>

Like poll_write, except that it writes from a slice of buffers. Read more
source§

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation. Read more
source§

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

Attempts to flush the object, ensuring that any buffered data reach their destination. Read more
source§

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

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down. Read more
source§

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

source§

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

Formats the value using the given formatter. Read more
source§

impl<RW> From<BufWriter<BufReader<RW>>> for BufStream<RW>

source§

fn from(b: BufWriter<BufReader<RW>>) -> Self

Converts to this type from the input type.
source§

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

Auto Trait Implementations§

§

impl<W> Freeze for BufWriter<W>
where W: Freeze,

§

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§

source§

impl<T> Any for T
where T: 'static + ?Sized,

source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
source§

impl<R> AsyncBufReadExt for R
where R: AsyncBufRead + ?Sized,

source§

fn read_until<'a>( &'a mut self, byte: u8, buf: &'a mut Vec<u8> ) -> ReadUntil<'a, Self>
where Self: Unpin,

Reads all bytes into buf until the delimiter byte or EOF is reached. Read more
source§

fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self>
where Self: Unpin,

Reads all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer. Read more
source§

fn split(self, byte: u8) -> Split<Self>
where Self: Sized + Unpin,

Returns a stream of the contents of this reader split on the byte byte. Read more
source§

fn fill_buf(&mut self) -> FillBuf<'_, Self>
where Self: Unpin,

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
source§

fn consume(&mut self, amt: usize)
where Self: Unpin,

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read. Read more
source§

fn lines(self) -> Lines<Self>
where Self: Sized,

Returns a stream over the lines of this reader. This method is the async equivalent to BufRead::lines. Read more
source§

impl<R> AsyncReadExt for R
where R: AsyncRead + ?Sized,

source§

fn chain<R>(self, next: R) -> Chain<Self, R>
where Self: Sized, R: AsyncRead,

Creates a new AsyncRead instance that chains this stream with next. Read more
source§

fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>
where Self: Unpin,

Pulls some bytes from this source into the specified buffer, returning how many bytes were read. Read more
source§

fn read_buf<'a, B>(&'a mut self, buf: &'a mut B) -> ReadBuf<'a, Self, B>
where Self: Unpin, B: BufMut + ?Sized,

Pulls some bytes from this source into the specified buffer, advancing the buffer’s internal cursor. Read more
source§

fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self>
where Self: Unpin,

Reads the exact number of bytes required to fill buf. Read more
source§

fn read_u8(&mut self) -> ReadU8<&mut Self>
where Self: Unpin,

Reads an unsigned 8 bit integer from the underlying reader. Read more
source§

fn read_i8(&mut self) -> ReadI8<&mut Self>
where Self: Unpin,

Reads a signed 8 bit integer from the underlying reader. Read more
source§

fn read_u16(&mut self) -> ReadU16<&mut Self>
where Self: Unpin,

Reads an unsigned 16-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_i16(&mut self) -> ReadI16<&mut Self>
where Self: Unpin,

Reads a signed 16-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_u32(&mut self) -> ReadU32<&mut Self>
where Self: Unpin,

Reads an unsigned 32-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_i32(&mut self) -> ReadI32<&mut Self>
where Self: Unpin,

Reads a signed 32-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_u64(&mut self) -> ReadU64<&mut Self>
where Self: Unpin,

Reads an unsigned 64-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_i64(&mut self) -> ReadI64<&mut Self>
where Self: Unpin,

Reads an signed 64-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_u128(&mut self) -> ReadU128<&mut Self>
where Self: Unpin,

Reads an unsigned 128-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_i128(&mut self) -> ReadI128<&mut Self>
where Self: Unpin,

Reads an signed 128-bit integer in big-endian order from the underlying reader. Read more
source§

fn read_f32(&mut self) -> ReadF32<&mut Self>
where Self: Unpin,

Reads an 32-bit floating point type in big-endian order from the underlying reader. Read more
source§

fn read_f64(&mut self) -> ReadF64<&mut Self>
where Self: Unpin,

Reads an 64-bit floating point type in big-endian order from the underlying reader. Read more
source§

fn read_u16_le(&mut self) -> ReadU16Le<&mut Self>
where Self: Unpin,

Reads an unsigned 16-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_i16_le(&mut self) -> ReadI16Le<&mut Self>
where Self: Unpin,

Reads a signed 16-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_u32_le(&mut self) -> ReadU32Le<&mut Self>
where Self: Unpin,

Reads an unsigned 32-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_i32_le(&mut self) -> ReadI32Le<&mut Self>
where Self: Unpin,

Reads a signed 32-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_u64_le(&mut self) -> ReadU64Le<&mut Self>
where Self: Unpin,

Reads an unsigned 64-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_i64_le(&mut self) -> ReadI64Le<&mut Self>
where Self: Unpin,

Reads an signed 64-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_u128_le(&mut self) -> ReadU128Le<&mut Self>
where Self: Unpin,

Reads an unsigned 128-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_i128_le(&mut self) -> ReadI128Le<&mut Self>
where Self: Unpin,

Reads an signed 128-bit integer in little-endian order from the underlying reader. Read more
source§

fn read_f32_le(&mut self) -> ReadF32Le<&mut Self>
where Self: Unpin,

Reads an 32-bit floating point type in little-endian order from the underlying reader. Read more
source§

fn read_f64_le(&mut self) -> ReadF64Le<&mut Self>
where Self: Unpin,

Reads an 64-bit floating point type in little-endian order from the underlying reader. Read more
source§

fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self>
where Self: Unpin,

Reads all bytes until EOF in this source, placing them into buf. Read more
source§

fn read_to_string<'a>( &'a mut self, dst: &'a mut String ) -> ReadToString<'a, Self>
where Self: Unpin,

Reads all bytes until EOF in this source, appending them to buf. Read more
source§

fn take(self, limit: u64) -> Take<Self>
where Self: Sized,

Creates an adaptor which reads at most limit bytes from it. Read more
source§

impl<S> AsyncSeekExt for S
where S: AsyncSeek + ?Sized,

source§

fn seek(&mut self, pos: SeekFrom) -> Seek<'_, Self>
where Self: Unpin,

Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more
source§

fn rewind(&mut self) -> Seek<'_, Self>
where Self: Unpin,

Creates a future which will rewind to the beginning of the stream. Read more
source§

fn stream_position(&mut self) -> Seek<'_, Self>
where Self: Unpin,

Creates a future which will return the current seek position from the start of the stream. Read more
source§

impl<W> AsyncWriteExt for W
where W: AsyncWrite + ?Sized,

source§

fn write<'a>(&'a mut self, src: &'a [u8]) -> Write<'a, Self>
where Self: Unpin,

Writes a buffer into this writer, returning how many bytes were written. Read more
source§

fn write_vectored<'a, 'b>( &'a mut self, bufs: &'a [IoSlice<'b>] ) -> WriteVectored<'a, 'b, Self>
where Self: Unpin,

Like write, except that it writes from a slice of buffers. Read more
source§

fn write_buf<'a, B>(&'a mut self, src: &'a mut B) -> WriteBuf<'a, Self, B>
where Self: Sized + Unpin, B: Buf,

Writes a buffer into this writer, advancing the buffer’s internal cursor. Read more
source§

fn write_all_buf<'a, B>( &'a mut self, src: &'a mut B ) -> WriteAllBuf<'a, Self, B>
where Self: Sized + Unpin, B: Buf,

Attempts to write an entire buffer into this writer. Read more
source§

fn write_all<'a>(&'a mut self, src: &'a [u8]) -> WriteAll<'a, Self>
where Self: Unpin,

Attempts to write an entire buffer into this writer. Read more
source§

fn write_u8(&mut self, n: u8) -> WriteU8<&mut Self>
where Self: Unpin,

Writes an unsigned 8-bit integer to the underlying writer. Read more
source§

fn write_i8(&mut self, n: i8) -> WriteI8<&mut Self>
where Self: Unpin,

Writes a signed 8-bit integer to the underlying writer. Read more
source§

fn write_u16(&mut self, n: u16) -> WriteU16<&mut Self>
where Self: Unpin,

Writes an unsigned 16-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_i16(&mut self, n: i16) -> WriteI16<&mut Self>
where Self: Unpin,

Writes a signed 16-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_u32(&mut self, n: u32) -> WriteU32<&mut Self>
where Self: Unpin,

Writes an unsigned 32-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_i32(&mut self, n: i32) -> WriteI32<&mut Self>
where Self: Unpin,

Writes a signed 32-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_u64(&mut self, n: u64) -> WriteU64<&mut Self>
where Self: Unpin,

Writes an unsigned 64-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_i64(&mut self, n: i64) -> WriteI64<&mut Self>
where Self: Unpin,

Writes an signed 64-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_u128(&mut self, n: u128) -> WriteU128<&mut Self>
where Self: Unpin,

Writes an unsigned 128-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_i128(&mut self, n: i128) -> WriteI128<&mut Self>
where Self: Unpin,

Writes an signed 128-bit integer in big-endian order to the underlying writer. Read more
source§

fn write_f32(&mut self, n: f32) -> WriteF32<&mut Self>
where Self: Unpin,

Writes an 32-bit floating point type in big-endian order to the underlying writer. Read more
source§

fn write_f64(&mut self, n: f64) -> WriteF64<&mut Self>
where Self: Unpin,

Writes an 64-bit floating point type in big-endian order to the underlying writer. Read more
source§

fn write_u16_le(&mut self, n: u16) -> WriteU16Le<&mut Self>
where Self: Unpin,

Writes an unsigned 16-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_i16_le(&mut self, n: i16) -> WriteI16Le<&mut Self>
where Self: Unpin,

Writes a signed 16-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_u32_le(&mut self, n: u32) -> WriteU32Le<&mut Self>
where Self: Unpin,

Writes an unsigned 32-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_i32_le(&mut self, n: i32) -> WriteI32Le<&mut Self>
where Self: Unpin,

Writes a signed 32-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_u64_le(&mut self, n: u64) -> WriteU64Le<&mut Self>
where Self: Unpin,

Writes an unsigned 64-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_i64_le(&mut self, n: i64) -> WriteI64Le<&mut Self>
where Self: Unpin,

Writes an signed 64-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_u128_le(&mut self, n: u128) -> WriteU128Le<&mut Self>
where Self: Unpin,

Writes an unsigned 128-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_i128_le(&mut self, n: i128) -> WriteI128Le<&mut Self>
where Self: Unpin,

Writes an signed 128-bit integer in little-endian order to the underlying writer. Read more
source§

fn write_f32_le(&mut self, n: f32) -> WriteF32Le<&mut Self>
where Self: Unpin,

Writes an 32-bit floating point type in little-endian order to the underlying writer. Read more
source§

fn write_f64_le(&mut self, n: f64) -> WriteF64Le<&mut Self>
where Self: Unpin,

Writes an 64-bit floating point type in little-endian order to the underlying writer. Read more
source§

fn flush(&mut self) -> Flush<'_, Self>
where Self: Unpin,

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
source§

fn shutdown(&mut self) -> Shutdown<'_, Self>
where Self: Unpin,

Shuts down the output stream, ensuring that the value can be dropped cleanly. Read more
source§

impl<T> Borrow<T> for T
where T: ?Sized,

source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

impl<T> BorrowMut<T> for T
where T: ?Sized,

source§

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

Mutably borrows from an owned value. Read more
source§

impl<T> From<T> for T

source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

impl<T, U> Into<U> for T
where U: From<T>,

source§

fn into(self) -> U

Calls U::from(self).

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

source§

impl<T, U> TryFrom<U> for T
where U: Into<T>,

§

type Error = Infallible

The type returned in the event of a conversion error.
source§

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

Performs the conversion.
source§

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

§

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

The type returned in the event of a conversion error.
source§

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

Performs the conversion.