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
sourceimpl<R> BufReader<R> where
R: AsyncRead,
impl<R> BufReader<R> where
R: AsyncRead,
sourcepub fn new(inner: R) -> BufReader<R>
pub fn new(inner: R) -> BufReader<R>
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) -> BufReader<R>
pub fn with_capacity(capacity: usize, inner: R) -> BufReader<R>
Creates a new BufReader
with the specified buffer capacity.
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 BufReader<R>>) -> Pin<&mut R>ⓘNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
pub fn get_pin_mut(self: Pin<&mut BufReader<R>>) -> Pin<&mut R>ⓘNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
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.
sourceimpl<R> BufReader<R> where
R: AsyncRead + AsyncSeek,
impl<R> BufReader<R> where
R: AsyncRead + AsyncSeek,
sourcepub fn seek_relative(
self: Pin<&mut BufReader<R>>,
offset: i64
) -> SeeKRelative<'_, R>ⓘNotable traits for SeeKRelative<'_, R>impl<'_, R> Future for SeeKRelative<'_, R> where
R: AsyncRead + AsyncSeek, type Output = Result<(), Error>;
pub fn seek_relative(
self: Pin<&mut BufReader<R>>,
offset: i64
) -> SeeKRelative<'_, R>ⓘNotable traits for SeeKRelative<'_, R>impl<'_, R> Future for SeeKRelative<'_, R> where
R: AsyncRead + AsyncSeek, type Output = Result<(), Error>;
R: AsyncRead + AsyncSeek, type Output = Result<(), Error>;
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 BufReader<R>>,
cx: &mut Context<'_>,
offset: i64
) -> Poll<Result<(), Error>>
pub fn poll_seek_relative(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
offset: i64
) -> Poll<Result<(), Error>>
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
sourceimpl<R> AsyncBufRead for BufReader<R> where
R: AsyncRead,
impl<R> AsyncBufRead for BufReader<R> where
R: AsyncRead,
sourceimpl<R> AsyncRead for BufReader<R> where
R: AsyncRead,
impl<R> AsyncRead for BufReader<R> where
R: AsyncRead,
sourceimpl<R> AsyncSeek for BufReader<R> where
R: AsyncRead + AsyncSeek,
impl<R> AsyncSeek for BufReader<R> where
R: AsyncRead + AsyncSeek,
sourcefn poll_seek(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
pos: SeekFrom
) -> Poll<Result<u64, Error>>
fn poll_seek(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
pos: SeekFrom
) -> Poll<Result<u64, Error>>
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)
.
sourceimpl<R> AsyncWrite for BufReader<R> where
R: AsyncWrite,
impl<R> AsyncWrite for BufReader<R> where
R: AsyncWrite,
sourcefn poll_write(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize, Error>>
fn poll_write(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize, Error>>
Attempt to write bytes from buf
into the object. Read more
sourcefn poll_write_vectored(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
bufs: &[IoSlice<'_>]
) -> Poll<Result<usize, Error>>
fn poll_write_vectored(
self: Pin<&mut BufReader<R>>,
cx: &mut Context<'_>,
bufs: &[IoSlice<'_>]
) -> Poll<Result<usize, Error>>
Attempt to write bytes from bufs
into the object using vectored
IO operations. 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], Error>;
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], Error>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8], Error>;
Creates a future which will wait for a non-empty buffer to be available from this I/O object or EOF to be reached. Read more
sourcefn consume_unpin(&mut self, amt: usize) where
Self: Unpin,
fn consume_unpin(&mut self, amt: usize) where
Self: Unpin,
A convenience for calling AsyncBufRead::consume
on Unpin
IO types. Read more
sourcefn read_until(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8, Global>
) -> ReadUntil<'a, Self>ⓘNotable traits for ReadUntil<'_, R>impl<'_, R> Future for ReadUntil<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_until(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8, Global>
) -> ReadUntil<'a, Self>ⓘNotable traits for ReadUntil<'_, R>impl<'_, R> Future for ReadUntil<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will read all the bytes associated with this I/O
object into buf
until the delimiter byte
or EOF is reached.
This method is the async equivalent to BufRead::read_until
. Read more
sourcefn read_line(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self>ⓘNotable traits for ReadLine<'_, R>impl<'_, R> Future for ReadLine<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_line(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self>ⓘNotable traits for ReadLine<'_, R>impl<'_, R> Future for ReadLine<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will read all the bytes associated with this I/O
object into buf
until a newline (the 0xA byte) or EOF is reached,
This method is the async equivalent to BufRead::read_line
. Read more
sourcefn lines(self) -> Lines<Self>
fn lines(self) -> Lines<Self>
Returns a stream over the lines of this reader.
This method is the async equivalent to BufRead::lines
. Read more
sourceimpl<R> AsyncReadExt for R where
R: AsyncRead + ?Sized,
impl<R> AsyncReadExt for R where
R: AsyncRead + ?Sized,
sourcefn chain<R>(self, next: R) -> Chain<Self, R> where
R: AsyncRead,
fn chain<R>(self, next: R) -> Chain<Self, R> where
R: AsyncRead,
Creates an adaptor which will chain this stream with another. Read more
sourcefn read(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>ⓘNotable traits for Read<'_, R>impl<'_, R> Future for Read<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>ⓘNotable traits for Read<'_, R>impl<'_, R> Future for Read<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Tries to read some bytes directly into the given buf
in asynchronous
manner, returning a future type. Read more
sourcefn read_vectored(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectored<'a, Self>ⓘNotable traits for ReadVectored<'_, R>impl<'_, R> Future for ReadVectored<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_vectored(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectored<'a, Self>ⓘNotable traits for ReadVectored<'_, R>impl<'_, R> Future for ReadVectored<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will read from the AsyncRead
into bufs
using vectored
IO operations. Read more
sourcefn read_exact(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self>ⓘNotable traits for ReadExact<'_, R>impl<'_, R> Future for ReadExact<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn read_exact(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self>ⓘNotable traits for ReadExact<'_, R>impl<'_, R> Future for ReadExact<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<(), Error>;
Creates a future which will read exactly enough bytes to fill buf
,
returning an error if end of file (EOF) is hit sooner. Read more
sourcefn read_to_end(
&'a mut self,
buf: &'a mut Vec<u8, Global>
) -> ReadToEnd<'a, Self>ⓘNotable traits for ReadToEnd<'_, A>impl<'_, A> Future for ReadToEnd<'_, A> where
A: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_to_end(
&'a mut self,
buf: &'a mut Vec<u8, Global>
) -> ReadToEnd<'a, Self>ⓘNotable traits for ReadToEnd<'_, A>impl<'_, A> Future for ReadToEnd<'_, A> where
A: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
A: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will read all the bytes from this AsyncRead
. Read more
sourcefn read_to_string(&'a mut self, buf: &'a mut String) -> ReadToString<'a, Self>ⓘNotable traits for ReadToString<'_, A>impl<'_, A> Future for ReadToString<'_, A> where
A: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_to_string(&'a mut self, buf: &'a mut String) -> ReadToString<'a, Self>ⓘNotable traits for ReadToString<'_, A>impl<'_, A> Future for ReadToString<'_, A> where
A: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
A: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will read all the bytes from this AsyncRead
. 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) -> Seek<'_, Self>ⓘNotable traits for Seek<'_, S>impl<'_, S> Future for Seek<'_, S> where
S: AsyncSeek + Unpin + ?Sized, type Output = Result<u64, Error>;
where
Self: Unpin,
fn seek(&mut self, pos: SeekFrom) -> Seek<'_, Self>ⓘNotable traits for Seek<'_, S>impl<'_, S> Future for Seek<'_, S> where
S: AsyncSeek + Unpin + ?Sized, type Output = Result<u64, Error>;
where
Self: Unpin,
S: AsyncSeek + Unpin + ?Sized, type Output = Result<u64, Error>;
Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more
sourcefn stream_position(&mut self) -> Seek<'_, Self>ⓘNotable traits for Seek<'_, S>impl<'_, S> Future for Seek<'_, S> where
S: AsyncSeek + Unpin + ?Sized, type Output = Result<u64, Error>;
where
Self: Unpin,
fn stream_position(&mut self) -> Seek<'_, Self>ⓘNotable traits for Seek<'_, S>impl<'_, S> Future for Seek<'_, S> where
S: AsyncSeek + Unpin + ?Sized, type Output = Result<u64, Error>;
where
Self: Unpin,
S: AsyncSeek + Unpin + ?Sized, type Output = Result<u64, Error>;
Creates a future which will return the current seek position from the start of the stream. Read more
sourceimpl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
impl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
sourcefn flush(&mut self) -> Flush<'_, Self>ⓘNotable traits for Flush<'_, W>impl<'_, W> Future for Flush<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn flush(&mut self) -> Flush<'_, Self>ⓘNotable traits for Flush<'_, W>impl<'_, W> Future for Flush<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Creates a future which will entirely flush this AsyncWrite
. Read more
sourcefn close(&mut self) -> Close<'_, Self>ⓘNotable traits for Close<'_, W>impl<'_, W> Future for Close<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn close(&mut self) -> Close<'_, Self>ⓘNotable traits for Close<'_, W>impl<'_, W> Future for Close<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Creates a future which will entirely close this AsyncWrite
.
sourcefn write(&'a mut self, buf: &'a [u8]) -> Write<'a, Self>ⓘNotable traits for Write<'_, W>impl<'_, W> Future for Write<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn write(&'a mut self, buf: &'a [u8]) -> Write<'a, Self>ⓘNotable traits for Write<'_, W>impl<'_, W> Future for Write<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will write bytes from buf
into the object. Read more
sourcefn write_vectored(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectored<'a, Self>ⓘNotable traits for WriteVectored<'_, W>impl<'_, W> Future for WriteVectored<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn write_vectored(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectored<'a, Self>ⓘNotable traits for WriteVectored<'_, W>impl<'_, W> Future for WriteVectored<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
Creates a future which will write bytes from bufs
into the object using vectored
IO operations. Read more
sourcefn write_all(&'a mut self, buf: &'a [u8]) -> WriteAll<'a, Self>ⓘNotable traits for WriteAll<'_, W>impl<'_, W> Future for WriteAll<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn write_all(&'a mut self, buf: &'a [u8]) -> WriteAll<'a, Self>ⓘNotable traits for WriteAll<'_, W>impl<'_, W> Future for WriteAll<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Write data into this object. Read more
sourcefn write_all_vectored(
&'a mut self,
bufs: &'a mut [IoSlice<'a>]
) -> WriteAllVectored<'a, Self>ⓘNotable traits for WriteAllVectored<'_, W>impl<'_, W> Future for WriteAllVectored<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn write_all_vectored(
&'a mut self,
bufs: &'a mut [IoSlice<'a>]
) -> WriteAllVectored<'a, Self>ⓘNotable traits for WriteAllVectored<'_, W>impl<'_, W> Future for WriteAllVectored<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Attempts to write multiple buffers into this writer. 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