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§
source§impl<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);
source§impl<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] ⓘ
pub fn buffer(&self) -> &[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§
source§impl<R: AsyncRead> AsyncBufRead for BufReader<R>
impl<R: AsyncRead> AsyncBufRead for BufReader<R>
source§fn poll_fill_buf<'a>(
self: Pin<&'a mut Self>,
cx: &mut Context<'_>
) -> Poll<Result<&'a [u8]>>
fn poll_fill_buf<'a>( self: Pin<&'a mut Self>, cx: &mut Context<'_> ) -> Poll<Result<&'a [u8]>>
source§impl<R: AsyncRead> AsyncRead for BufReader<R>
impl<R: AsyncRead> AsyncRead for BufReader<R>
source§impl<R: AsyncSeek> AsyncSeek for BufReader<R>
impl<R: AsyncSeek> AsyncSeek for BufReader<R>
source§fn 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)
.
source§impl<R: AsyncWrite> AsyncWrite for BufReader<R>
impl<R: AsyncWrite> AsyncWrite for BufReader<R>
source§fn 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>>
buf
into the object. Read moresource§fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
impl<'__pin, R> Unpin for BufReader<R>where
__Origin<'__pin, R>: Unpin,
Auto Trait Implementations§
impl<R> Freeze for BufReader<R>where
R: Freeze,
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§
source§impl<R> AsyncBufReadExt for Rwhere
R: AsyncBufRead + ?Sized,
impl<R> AsyncBufReadExt for Rwhere
R: AsyncBufRead + ?Sized,
source§fn fill_buf(&mut self) -> FillBuf<'_, Self> ⓘwhere
Self: Unpin,
fn fill_buf(&mut self) -> FillBuf<'_, Self> ⓘwhere
Self: Unpin,
source§fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>
) -> ReadUntilFuture<'_, Self> ⓘwhere
Self: Unpin,
fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>
) -> ReadUntilFuture<'_, Self> ⓘwhere
Self: Unpin,
source§fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLineFuture<'_, Self> ⓘwhere
Self: Unpin,
fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLineFuture<'_, Self> ⓘwhere
Self: Unpin,
buf
until a newline (the 0xA byte) or EOF is found. Read moresource§impl<R> AsyncReadExt for R
impl<R> AsyncReadExt for R
source§fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadFuture<'a, Self> ⓘwhere
Self: Unpin,
fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectoredFuture<'a, Self> ⓘwhere
Self: Unpin,
fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectoredFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn read_to_end<'a>(
&'a mut self,
buf: &'a mut Vec<u8>
) -> ReadToEndFuture<'a, Self> ⓘwhere
Self: Unpin,
fn read_to_end<'a>(
&'a mut self,
buf: &'a mut Vec<u8>
) -> ReadToEndFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String
) -> ReadToStringFuture<'a, Self> ⓘwhere
Self: Unpin,
fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String
) -> ReadToStringFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExactFuture<'a, Self> ⓘwhere
Self: Unpin,
fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExactFuture<'a, Self> ⓘwhere
Self: Unpin,
buf
. Read moresource§fn take(self, limit: u64) -> Take<Self>where
Self: Sized,
fn take(self, limit: u64) -> Take<Self>where
Self: Sized,
limit
bytes from it. Read moresource§impl<S> AsyncSeekExt for S
impl<S> AsyncSeekExt for S
source§impl<W> AsyncWriteExt for Wwhere
W: AsyncWrite + ?Sized,
impl<W> AsyncWriteExt for Wwhere
W: AsyncWrite + ?Sized,
source§fn write<'a>(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self> ⓘwhere
Self: Unpin,
fn write<'a>(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectoredFuture<'a, Self> ⓘwhere
Self: Unpin,
fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectoredFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self> ⓘwhere
Self: Unpin,
fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self> ⓘwhere
Self: Unpin,
source§fn flush(&mut self) -> FlushFuture<'_, Self> ⓘwhere
Self: Unpin,
fn flush(&mut self) -> FlushFuture<'_, Self> ⓘwhere
Self: Unpin,
source§fn boxed_writer<'a>(self) -> Pin<Box<dyn AsyncWrite + Send + 'a>>
fn boxed_writer<'a>(self) -> Pin<Box<dyn AsyncWrite + Send + 'a>>
dyn AsyncWrite + Send + 'a
. Read more