Struct fuchsia_fs::file::AsyncReader

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pub struct AsyncReader { /* private fields */ }
Expand description

Wraps a fidl_fuchsia_io::FileProxy and implements futures::io::AsyncRead, which allows one to perform asynchronous file reads that don’t block the current thread while waiting for data.

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impl AsyncReader

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pub fn from_proxy(file: FileProxy) -> Result<Self, AsyncReaderError>

Errors if the provided FileProxy does not exclusively own the wrapped channel.

Exclusive ownership avoids surprising behavior arising from the mismatch between the semantics for AsyncRead and fuchsia.io/File.Read. On e.g. Linux, if two AsyncRead objects were wrapping the same file descriptor and a call to poll_read on one of the AsyncRead objects returned Pending, a client would generally not expect the offset of the underlying file descriptor to advance. Meaning that a client could then call poll_read on the other AsyncRead object and expect not to miss any file contents. However, with an AsyncRead implementation that wraps fuchsia.io/File.Read, a poll_read call that returns Pending would advance the file offset, meaning that interleaving usage of AsyncRead objects that share a channel would return file contents in surprising order.

Trait Implementations§

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impl AsyncRead for AsyncReader

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fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize>>

Attempt to read from the AsyncRead into buf. Read more
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fn poll_read_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &mut [IoSliceMut<'_>], ) -> Poll<Result<usize, Error>>

Attempt to read from the AsyncRead into bufs using vectored IO operations. Read more
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impl Debug for AsyncReader

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<R> AsyncReadExt for R
where R: AsyncRead + ?Sized,

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fn chain<R>(self, next: R) -> Chain<Self, R>
where Self: Sized, R: AsyncRead,

Creates an adaptor which will chain this stream with another. Read more
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fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>
where Self: Unpin,

Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type. Read more
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fn read_vectored<'a>( &'a mut self, bufs: &'a mut [IoSliceMut<'a>], ) -> ReadVectored<'a, Self>
where Self: Unpin,

Creates a future which will read from the AsyncRead into bufs using vectored IO operations. Read more
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fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self>
where Self: Unpin,

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
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fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self>
where Self: Unpin,

Creates a future which will read all the bytes from this AsyncRead. Read more
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fn read_to_string<'a>( &'a mut self, buf: &'a mut String, ) -> ReadToString<'a, Self>
where Self: Unpin,

Creates a future which will read all the bytes from this AsyncRead. Read more
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fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>)
where Self: Sized + AsyncWrite,

Helper method for splitting this read/write object into two halves. Read more
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fn take(self, limit: u64) -> Take<Self>
where Self: Sized,

Creates an AsyncRead adapter which will read at most limit bytes from the underlying reader. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T, D> Encode<Ambiguous1, D> for T
where D: ResourceDialect,

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unsafe fn encode( self, _encoder: &mut Encoder<'_, D>, _offset: usize, _depth: Depth, ) -> Result<(), Error>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for Handle::INVALID. Read more
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impl<T, D> Encode<Ambiguous2, D> for T
where D: ResourceDialect,

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unsafe fn encode( self, _encoder: &mut Encoder<'_, D>, _offset: usize, _depth: Depth, ) -> Result<(), Error>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for Handle::INVALID. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [Span], returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a [WithDispatch] wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a [WithDispatch] wrapper. Read more