[−][src]Trait futures_util::io::AsyncWrite

pub trait AsyncWrite {
    fn poll_write(
        &mut self, 
        lw: &LocalWaker, 
        buf: &[u8]
    ) -> Poll<Result<usize, Error>>;

    fn poll_flush(&mut self, lw: &LocalWaker) -> Poll<Result<(), Error>>;

    fn poll_close(&mut self, lw: &LocalWaker) -> Poll<Result<(), Error>>;

    fn poll_vectored_write(
        &mut self, 
        lw: &LocalWaker, 
        vec: &[&IoVec]
    ) -> Poll<Result<usize, Error>> { ... }
}

Write bytes asynchronously.

This trait is analogous to the std::io::Write trait, but integrates with the asynchronous task system. In particular, the poll_write method, unlike Write::write, will automatically queue the current task for wakeup and return if data is not yet available, rather than blocking the calling thread.

Required Methods

Attempt to write bytes from buf into the object.

On success, returns Ok(Async::Ready(num_bytes_written)).

If the object is not ready for writing, the method returns Ok(Async::Pending) and arranges for the current task (via lw.waker()) to receive a notification when the object becomes readable or is closed.

Implementation

This function may not return errors of kind WouldBlock or Interrupted. Implementations must convert WouldBlock into Async::Pending and either internally retry or convert Interrupted into another error kind.

Attempt to flush the object, ensuring that any buffered data reach their destination.

On success, returns Ok(Async::Ready(())).

If flushing cannot immediately complete, this method returns Ok(Async::Pending) and arranges for the current task (via lw.waker()) to receive a notification when the object can make progress towards flushing.

Implementation

This function may not return errors of kind WouldBlock or Interrupted. Implementations must convert WouldBlock into Async::Pending and either internally retry or convert Interrupted into another error kind.

Attempt to close the object.

On success, returns Ok(Async::Ready(())).

If closing cannot immediately complete, this function returns Ok(Async::Pending) and arranges for the current task (via lw.waker()) to receive a notification when the object can make progress towards closing.

Implementation

This function may not return errors of kind WouldBlock or Interrupted. Implementations must convert WouldBlock into Async::Pending and either internally retry or convert Interrupted into another error kind.

Provided Methods

Attempt to write bytes from vec into the object using vectored IO operations.

This method is similar to poll_write, but allows data from multiple buffers to be written using a single operation.

On success, returns Ok(Async::Ready(num_bytes_written)).

If the object is not ready for writing, the method returns Ok(Async::Pending) and arranges for the current task (via lw.waker()) to receive a notification when the object becomes readable or is closed.

By default, this method delegates to using poll_write on the first buffer in vec. Objects which support vectored IO should override this method.

Implementation

This function may not return errors of kind WouldBlock or Interrupted. Implementations must convert WouldBlock into Async::Pending and either internally retry or convert Interrupted into another error kind.

Implementations on Foreign Types

impl AsyncWrite for Sink
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impl<T> AsyncWrite for Box<T> where
    T: AsyncWrite + ?Sized, 
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impl<'a, T> AsyncWrite for &'a mut T where
    T: AsyncWrite + ?Sized, 
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impl<T> AsyncWrite for Cursor<T> where
    T: AsMut<[u8]>, 
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Implementors

impl<T> AsyncWrite for AllowStdIo<T> where
    T: Write, 
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impl<W: AsyncWrite> AsyncWrite for WriteHalf<W>
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impl<W: AsyncWrite01> AsyncWrite for Compat01As03<W>
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