pub struct BufReader<R> { /* private fields */ }
Expand description
The BufReader
struct adds buffering to any reader.
It can be excessively inefficient to work directly with a AsyncRead
instance. A BufReader
performs large, infrequent reads on the underlying
AsyncRead
and maintains an in-memory buffer of the results.
BufReader
can improve the speed of programs that make small and
repeated read calls to the same file or network socket. It does not
help when reading very large amounts at once, or reading just one or a few
times. It also provides no advantage when reading from a source that is
already in memory, like a Vec<u8>
.
When the BufReader
is dropped, the contents of its buffer will be
discarded. Creating multiple instances of a BufReader
on the same
stream can cause data loss.
Implementations§
source§impl<R: AsyncRead> BufReader<R>
impl<R: AsyncRead> BufReader<R>
sourcepub fn new(inner: R) -> Self
pub fn new(inner: R) -> Self
Creates a new BufReader
with a default buffer capacity. The default is currently 8 KB,
but may change in the future.
sourcepub fn with_capacity(capacity: usize, inner: R) -> Self
pub fn with_capacity(capacity: usize, inner: R) -> Self
Creates a new BufReader
with the specified buffer capacity.
source§impl<R> BufReader<R>
impl<R> BufReader<R>
sourcepub fn get_ref(&self) -> &R
pub fn get_ref(&self) -> &R
Acquires a reference to the underlying sink or stream that this combinator is pulling from.
sourcepub fn get_mut(&mut self) -> &mut R
pub fn get_mut(&mut self) -> &mut R
Acquires a mutable reference to the underlying sink or stream that this combinator is pulling from.
Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.
sourcepub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R>
pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R>
Acquires a pinned mutable reference to the underlying sink or stream that this combinator is pulling from.
Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.
sourcepub fn into_inner(self) -> R
pub fn into_inner(self) -> R
Consumes this combinator, returning the underlying sink or stream.
Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.
source§impl<R: AsyncRead + AsyncSeek> BufReader<R>
impl<R: AsyncRead + AsyncSeek> BufReader<R>
sourcepub fn seek_relative(self: Pin<&mut Self>, offset: i64) -> SeeKRelative<'_, R> ⓘ
pub fn seek_relative(self: Pin<&mut Self>, offset: i64) -> SeeKRelative<'_, R> ⓘ
Seeks relative to the current position. If the new position lies within the buffer, the buffer will not be flushed, allowing for more efficient seeks. This method does not return the location of the underlying reader, so the caller must track this information themselves if it is required.
sourcepub fn poll_seek_relative(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
offset: i64,
) -> Poll<Result<()>>
pub fn poll_seek_relative( self: Pin<&mut Self>, cx: &mut Context<'_>, offset: i64, ) -> Poll<Result<()>>
Attempts to seek relative to the current position. If the new position lies within the buffer, the buffer will not be flushed, allowing for more efficient seeks. This method does not return the location of the underlying reader, so the caller must track this information themselves if it is required.
Trait Implementations§
source§impl<R: AsyncRead> AsyncBufRead for BufReader<R>
impl<R: AsyncRead> AsyncBufRead for BufReader<R>
source§impl<R: AsyncRead> AsyncRead for BufReader<R>
impl<R: AsyncRead> AsyncRead for BufReader<R>
source§impl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R>
impl<R: AsyncRead + 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>>
Seek 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.
To seek without discarding the internal buffer, use
BufReader::seek_relative
or
BufReader::poll_seek_relative
.
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_write_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &[IoSlice<'_>],
) -> Poll<Result<usize>>
fn poll_write_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize>>
bufs
into the object using vectored
IO operations. Read moreimpl<'__pin, R> Unpin for BufReader<R>where
PinnedFieldsOf<__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 consume_unpin(&mut self, amt: usize)where
Self: Unpin,
fn consume_unpin(&mut self, amt: usize)where
Self: Unpin,
source§fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>,
) -> ReadUntil<'a, Self> ⓘwhere
Self: Unpin,
fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>,
) -> ReadUntil<'a, Self> ⓘwhere
Self: Unpin,
buf
until the delimiter byte
or EOF is reached.
This method is the async equivalent to BufRead::read_until
. Read moresource§fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self> ⓘwhere
Self: Unpin,
fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self> ⓘwhere
Self: Unpin,
buf
until a newline (the 0xA byte) or EOF is reached,
This method is the async equivalent to BufRead::read_line
. Read moresource§impl<R> AsyncReadExt for R
impl<R> AsyncReadExt for R
source§fn chain<R>(self, next: R) -> Chain<Self, R>
fn chain<R>(self, next: R) -> Chain<Self, R>
source§fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self> ⓘwhere
Self: Unpin,
fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self> ⓘwhere
Self: Unpin,
buf
in asynchronous
manner, returning a future type. Read moresource§fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>],
) -> ReadVectored<'a, Self> ⓘwhere
Self: Unpin,
fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>],
) -> ReadVectored<'a, Self> ⓘwhere
Self: Unpin,
AsyncRead
into bufs
using vectored
IO operations. Read moresource§fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self> ⓘwhere
Self: Unpin,
fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self> ⓘwhere
Self: Unpin,
buf
,
returning an error if end of file (EOF) is hit sooner. Read moresource§fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self> ⓘwhere
Self: Unpin,
fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self> ⓘwhere
Self: Unpin,
AsyncRead
. Read moresource§fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String,
) -> ReadToString<'a, Self> ⓘwhere
Self: Unpin,
fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String,
) -> ReadToString<'a, Self> ⓘwhere
Self: Unpin,
AsyncRead
. 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 flush(&mut self) -> Flush<'_, Self> ⓘwhere
Self: Unpin,
fn flush(&mut self) -> Flush<'_, Self> ⓘwhere
Self: Unpin,
AsyncWrite
. Read moresource§fn close(&mut self) -> Close<'_, Self> ⓘwhere
Self: Unpin,
fn close(&mut self) -> Close<'_, Self> ⓘwhere
Self: Unpin,
AsyncWrite
.source§fn write<'a>(&'a mut self, buf: &'a [u8]) -> Write<'a, Self> ⓘwhere
Self: Unpin,
fn write<'a>(&'a mut self, buf: &'a [u8]) -> Write<'a, Self> ⓘwhere
Self: Unpin,
buf
into the object. Read moresource§fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>],
) -> WriteVectored<'a, Self> ⓘwhere
Self: Unpin,
fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>],
) -> WriteVectored<'a, Self> ⓘwhere
Self: Unpin,
bufs
into the object using vectored
IO operations. Read more