[][src]Struct futures::io::BufReader

pub struct BufReader<R> { /* fields omitted */ }

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.

Methods

impl<R> BufReader<R> where
    R: AsyncRead
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pub fn new(inner: R) -> BufReader<R>[src]

Creates a new BufReader with a default buffer capacity. The default is currently 8 KB, but may change in the future.

pub fn with_capacity(capacity: usize, inner: R) -> BufReader<R>[src]

Creates a new BufReader with the specified buffer capacity.

Important traits for &'_ mut F
pub fn get_ref(&self) -> &R[src]

Gets a reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

Important traits for &'_ mut F
pub fn get_mut(&mut self) -> &mut R[src]

Gets a mutable reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

Important traits for Pin<P>
pub fn get_pin_mut(self: Pin<&mut BufReader<R>>) -> Pin<&mut R>[src]

Gets a pinned mutable reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

pub fn into_inner(self) -> R[src]

Consumes this BufWriter, returning the underlying reader.

Note that any leftover data in the internal buffer is lost.

Important traits for &'_ [u8]
pub fn buffer(&self) -> &[u8][src]

Returns a reference to the internally buffered data.

Unlike fill_buf, this will not attempt to fill the buffer if it is empty.

impl<R> BufReader<R> where
    R: AsyncRead + AsyncSeek
[src]

pub fn poll_seek_relative(
    self: Pin<&mut BufReader<R>>,
    cx: &mut Context,
    offset: i64
) -> Poll<Result<(), Error>>
[src]

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.

Trait Implementations

impl<R> AsyncSeek for BufReader<R> where
    R: AsyncRead + AsyncSeek
[src]

fn poll_seek(
    self: Pin<&mut BufReader<R>>,
    cx: &mut Context,
    pos: SeekFrom
) -> Poll<Result<u64, Error>>
[src]

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::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).

impl<R> AsyncBufRead for BufReader<R> where
    R: AsyncRead
[src]

impl<R> AsyncRead for BufReader<R> where
    R: AsyncRead
[src]

impl<R> Debug for BufReader<R> where
    R: Debug + AsyncRead
[src]

Auto Trait Implementations

impl<R> Send for BufReader<R> where
    R: Send

impl<R> Unpin for BufReader<R> where
    R: Unpin

impl<R> Sync for BufReader<R> where
    R: Sync

impl<R> UnwindSafe for BufReader<R> where
    R: UnwindSafe

impl<R> RefUnwindSafe for BufReader<R> where
    R: RefUnwindSafe

Blanket Implementations

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T> From<T> for T[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<R> AsyncReadExt for R where
    R: AsyncRead + ?Sized
[src]

impl<S> AsyncSeekExt for S where
    S: AsyncSeek + ?Sized
[src]

impl<R> AsyncBufReadExt for R where
    R: AsyncBufRead + ?Sized
[src]