Struct futures_lite::io::BufReader
source · [−]pub struct BufReader<R> { /* private fields */ }
Expand description
Adds buffering to a reader.
It can be excessively inefficient to work directly with an AsyncRead
instance. A
BufReader
performs large, infrequent reads on the underlying AsyncRead
and
maintains an in-memory buffer of the incoming byte stream.
BufReader
can improve the speed of programs that make small and repeated reads to
the same file or networking socket. It does not help when reading very large amounts at
once, or reading just once or a few times. It also provides no advantage when reading from
a source that is already in memory, like a Vec<u8>
.
When a BufReader
is dropped, the contents of its buffer are discarded. Creating
multiple instances of BufReader
on the same reader can cause data loss.
Examples
use futures_lite::io::{AsyncBufReadExt, BufReader};
let input: &[u8] = b"hello";
let mut reader = BufReader::new(input);
let mut line = String::new();
reader.read_line(&mut line).await?;
Implementations
sourceimpl<R: AsyncRead> BufReader<R>
impl<R: AsyncRead> BufReader<R>
sourcepub fn new(inner: R) -> BufReader<R>
pub fn new(inner: R) -> BufReader<R>
Creates a buffered reader with the default buffer capacity.
The default capacity is currently 8 KB, but that may change in the future.
Examples
use futures_lite::io::BufReader;
let input: &[u8] = b"hello";
let reader = BufReader::new(input);
sourcepub fn with_capacity(capacity: usize, inner: R) -> BufReader<R>
pub fn with_capacity(capacity: usize, inner: R) -> BufReader<R>
Creates a buffered reader with the specified capacity.
Examples
use futures_lite::io::BufReader;
let input: &[u8] = b"hello";
let reader = BufReader::with_capacity(1024, input);
sourceimpl<R> BufReader<R>
impl<R> BufReader<R>
sourcepub fn get_ref(&self) -> &R
pub fn get_ref(&self) -> &R
Gets a reference to the underlying reader.
It is not advisable to directly read from the underlying reader.
Examples
use futures_lite::io::BufReader;
let input: &[u8] = b"hello";
let reader = BufReader::new(input);
let r = reader.get_ref();
sourcepub fn get_mut(&mut self) -> &mut R
pub fn get_mut(&mut self) -> &mut R
Gets a mutable reference to the underlying reader.
It is not advisable to directly read from the underlying reader.
Examples
use futures_lite::io::BufReader;
let input: &[u8] = b"hello";
let mut reader = BufReader::new(input);
let r = reader.get_mut();
sourcepub fn buffer(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
pub fn buffer(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
Returns a reference to the internal buffer.
This method will not attempt to fill the buffer if it is empty.
Examples
use futures_lite::io::BufReader;
let input: &[u8] = b"hello";
let reader = BufReader::new(input);
// The internal buffer is empty until the first read request.
assert_eq!(reader.buffer(), &[]);
sourcepub fn into_inner(self) -> R
pub fn into_inner(self) -> R
Unwraps the buffered reader, returning the underlying reader.
Note that any leftover data in the internal buffer will be lost.
Examples
use futures_lite::io::BufReader;
let input: &[u8] = b"hello";
let reader = BufReader::new(input);
assert_eq!(reader.into_inner(), input);
Trait Implementations
sourceimpl<R: AsyncRead> AsyncBufRead for BufReader<R>
impl<R: AsyncRead> AsyncBufRead for BufReader<R>
sourceimpl<R: AsyncRead> AsyncRead for BufReader<R>
impl<R: AsyncRead> AsyncRead for BufReader<R>
sourceimpl<R: AsyncSeek> AsyncSeek for BufReader<R>
impl<R: AsyncSeek> AsyncSeek for BufReader<R>
sourcefn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom
) -> Poll<Result<u64>>
fn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom
) -> Poll<Result<u64>>
Seeks 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)
.
sourceimpl<R: AsyncWrite> AsyncWrite for BufReader<R>
impl<R: AsyncWrite> AsyncWrite for BufReader<R>
sourcefn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
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
sourcefn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
Attempt to flush the object, ensuring that any buffered data reach their destination. Read more
impl<'__pin, R> Unpin for BufReader<R> where
__Origin<'__pin, R>: Unpin,
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
sourceimpl<R> AsyncBufReadExt for R where
R: AsyncBufRead + ?Sized,
impl<R> AsyncBufReadExt for R where
R: AsyncBufRead + ?Sized,
sourcefn fill_buf(&mut self) -> FillBuf<'_, Self>ⓘNotable traits for FillBuf<'a, R>impl<'a, R> Future for FillBuf<'a, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8]>;
where
Self: Unpin,
fn fill_buf(&mut self) -> FillBuf<'_, Self>ⓘNotable traits for FillBuf<'a, R>impl<'a, R> Future for FillBuf<'a, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8]>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8]>;
Returns the contents of the internal buffer, filling it with more data if empty. Read more
sourcefn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>
) -> ReadUntilFuture<'_, Self>ⓘNotable traits for ReadUntilFuture<'_, R>impl<R: AsyncBufRead + Unpin + ?Sized> Future for ReadUntilFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>
) -> ReadUntilFuture<'_, Self>ⓘNotable traits for ReadUntilFuture<'_, R>impl<R: AsyncBufRead + Unpin + ?Sized> Future for ReadUntilFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
Reads all bytes and appends them into buf
until the delimiter byte
or EOF is found. Read more
sourcefn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLineFuture<'_, Self>ⓘNotable traits for ReadLineFuture<'_, R>impl<R: AsyncBufRead + Unpin + ?Sized> Future for ReadLineFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLineFuture<'_, Self>ⓘNotable traits for ReadLineFuture<'_, R>impl<R: AsyncBufRead + Unpin + ?Sized> Future for ReadLineFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
Reads all bytes and appends them into buf
until a newline (the 0xA byte) or EOF is found. Read more
sourceimpl<R> AsyncReadExt for R where
R: AsyncRead + ?Sized,
impl<R> AsyncReadExt for R where
R: AsyncRead + ?Sized,
sourcefn read<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadFuture<'a, Self>ⓘNotable traits for ReadFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadFuture<'a, Self>ⓘNotable traits for ReadFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
Reads some bytes from the byte stream. Read more
sourcefn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectoredFuture<'a, Self>ⓘNotable traits for ReadVectoredFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadVectoredFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectoredFuture<'a, Self>ⓘNotable traits for ReadVectoredFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadVectoredFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
sourcefn read_to_end<'a>(
&'a mut self,
buf: &'a mut Vec<u8>
) -> ReadToEndFuture<'a, Self>ⓘNotable traits for ReadToEndFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadToEndFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
fn read_to_end<'a>(
&'a mut self,
buf: &'a mut Vec<u8>
) -> ReadToEndFuture<'a, Self>ⓘNotable traits for ReadToEndFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadToEndFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
sourcefn read_to_string<'a>(
&'a mut self,
buf: &'a mut String
) -> ReadToStringFuture<'a, Self>ⓘNotable traits for ReadToStringFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadToStringFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String
) -> ReadToStringFuture<'a, Self>ⓘNotable traits for ReadToStringFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadToStringFuture<'_, R> type Output = Result<usize>;
where
Self: Unpin,
sourcefn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExactFuture<'a, Self>ⓘNotable traits for ReadExactFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadExactFuture<'_, R> type Output = Result<()>;
where
Self: Unpin,
fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExactFuture<'a, Self>ⓘNotable traits for ReadExactFuture<'_, R>impl<R: AsyncRead + Unpin + ?Sized> Future for ReadExactFuture<'_, R> type Output = Result<()>;
where
Self: Unpin,
Reads the exact number of bytes required to fill buf
. Read more
sourcefn take(self, limit: u64) -> Take<Self> where
Self: Sized,
fn take(self, limit: u64) -> Take<Self> where
Self: Sized,
Creates an adapter which will read at most limit
bytes from it. Read more
sourceimpl<S> AsyncSeekExt for S where
S: AsyncSeek + ?Sized,
impl<S> AsyncSeekExt for S where
S: AsyncSeek + ?Sized,
sourcefn seek(&mut self, pos: SeekFrom) -> SeekFuture<'_, Self>ⓘNotable traits for SeekFuture<'_, S>impl<S: AsyncSeek + Unpin + ?Sized> Future for SeekFuture<'_, S> type Output = Result<u64>;
where
Self: Unpin,
fn seek(&mut self, pos: SeekFrom) -> SeekFuture<'_, Self>ⓘNotable traits for SeekFuture<'_, S>impl<S: AsyncSeek + Unpin + ?Sized> Future for SeekFuture<'_, S> type Output = Result<u64>;
where
Self: Unpin,
Seeks to a new position in a byte stream. Read more
sourceimpl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
impl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
sourcefn write<'a>(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self>ⓘNotable traits for WriteFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for WriteFuture<'_, W> type Output = Result<usize>;
where
Self: Unpin,
fn write<'a>(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self>ⓘNotable traits for WriteFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for WriteFuture<'_, W> type Output = Result<usize>;
where
Self: Unpin,
Writes some bytes into the byte stream. Read more
sourcefn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectoredFuture<'a, Self>ⓘNotable traits for WriteVectoredFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for WriteVectoredFuture<'_, W> type Output = Result<usize>;
where
Self: Unpin,
fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectoredFuture<'a, Self>ⓘNotable traits for WriteVectoredFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for WriteVectoredFuture<'_, W> type Output = Result<usize>;
where
Self: Unpin,
sourcefn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self>ⓘNotable traits for WriteAllFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for WriteAllFuture<'_, W> type Output = Result<()>;
where
Self: Unpin,
fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self>ⓘNotable traits for WriteAllFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for WriteAllFuture<'_, W> type Output = Result<()>;
where
Self: Unpin,
Writes an entire buffer into the byte stream. Read more
sourcefn flush(&mut self) -> FlushFuture<'_, Self>ⓘNotable traits for FlushFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for FlushFuture<'_, W> type Output = Result<()>;
where
Self: Unpin,
fn flush(&mut self) -> FlushFuture<'_, Self>ⓘNotable traits for FlushFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for FlushFuture<'_, W> type Output = Result<()>;
where
Self: Unpin,
Flushes the stream to ensure that all buffered contents reach their destination. Read more
sourcefn close(&mut self) -> CloseFuture<'_, Self>ⓘNotable traits for CloseFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for CloseFuture<'_, W> type Output = Result<()>;
where
Self: Unpin,
fn close(&mut self) -> CloseFuture<'_, Self>ⓘNotable traits for CloseFuture<'_, W>impl<W: AsyncWrite + Unpin + ?Sized> Future for CloseFuture<'_, W> type Output = Result<()>;
where
Self: Unpin,
Closes the writer. Read more
sourcefn boxed_writer<'a>(self) -> Pin<Box<dyn AsyncWrite + Send + 'a>> where
Self: Sized + Send + 'a,
fn boxed_writer<'a>(self) -> Pin<Box<dyn AsyncWrite + Send + 'a>> where
Self: Sized + Send + 'a,
Boxes the writer and changes its type to dyn AsyncWrite + Send + 'a
. Read more
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more