Struct Reader

pub struct Reader(/* private fields */);

Read half of a stream. See stream().

Implementations

impl Reader

pub fn inspect_shutdown(&self) -> String

Debug

pub async fn read<F, U>(&self, size: usize, f: F) -> Result<U>

where F: FnMut(&[u8]) -> Result<(U, usize)>,

Read bytes from the stream.

The reader will wait until there are at least size bytes to read, Then it will call the given callback with a slice containing all available bytes to read.

If the callback processes data successfully, it should return Ok with a tuple containing a value of the user’s choice, and the number of bytes used. If the number of bytes returned from the callback is less than what was available in the buffer, the unused bytes will appear at the start of the buffer for subsequent read calls. It is allowable to peek at the bytes in the buffer by returning a number of bytes read that is smaller than the number of bytes actually used.

If the callback returns Error::BufferTooShort and the expected buffer value contained in the error is larger than the data that was provided, we will wait again until there are enough bytes to satisfy the error and then call the callback again. If the callback returns Error::BufferTooShort but the buffer should have been long enough according to the error, Error::CallbackRejectedBuffer is returned. Other errors from the callback are returned as-is from read itself.

If there are no bytes available to read and the Writer for this stream has already been dropped, read returns Error::ConnectionClosed. If there are not enough bytes available to be read and the Writer has been dropped, read returns Error::BufferTooSmall. This is the only time read should return Error::BufferTooSmall.

Panics if the callback returns a number of bytes greater than the size of the buffer.

pub fn poll_read<F, U>( &self, ctx: &mut Context<'_>, size: &mut usize, f: F, ) -> Poll<Result<U>>

where F: FnMut(&mut Context<'_>, &[u8]) -> Poll<Result<(U, usize)>>,

Like read but a poll function rather than a future. Passes the Context to the callback so the callback can also poll.

The size argument is a mutable reference so that if we determine during reading that more data is needed, we can update the size. It should always increase. The value of size is not meaningful after returning Poll::Ready.

pub async fn read_protocol_message<P: ProtocolMessage>(&self) -> Result<P>

Read a protocol message from the stream. This is just a quick way to wire ProtocolObject::try_from_bytes in to read.

pub fn is_closed(&self) -> bool

Whether this stream is closed. Returns false so long as there is unread data in the buffer, even if the writer has hung up.

pub fn closed_reason(&self) -> Option<String>

Get the reason this reader is closed. If the reader is not closed, or if no reason was given, return None.

pub fn close(self, reason: String)

Close this stream, giving a reason for the closure.

Trait Implementations

impl Debug for Reader

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

Formats the value using the given formatter.

impl Drop for Reader

fn drop(&mut self)

Executes the destructor for this type.