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: 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.
sourcepub fn get_ref(&self) -> &R
pub fn get_ref(&self) -> &R
Gets a reference to the underlying reader.
It is inadvisable to directly read from the underlying reader.
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 inadvisable to directly read from the underlying reader.
sourcepub fn get_pin_mut(self: Pin<&mut Self>) -> 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 Self>) -> 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;
Gets a pinned mutable reference to the underlying reader.
It is inadvisable to directly read from the underlying reader.
sourcepub fn into_inner(self) -> R
pub fn into_inner(self) -> R
Consumes this BufReader
, returning the underlying reader.
Note that any leftover data in the internal buffer is lost.
Trait Implementations
sourceimpl<R: AsyncRead> AsyncBufRead for BufReader<R>
impl<R: AsyncRead> AsyncBufRead for BufReader<R>
sourceimpl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R>
impl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R>
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: AsyncRead + AsyncWrite> AsyncWrite for BufReader<R>
impl<R: AsyncRead + 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_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>>
Like poll_write
, except that it writes from a slice of buffers. Read more
sourcefn is_write_vectored(&self) -> bool
fn is_write_vectored(&self) -> bool
Determines if this writer has an efficient poll_write_vectored
implementation. 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<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