Trait Body

pub trait Body

Trait representing a streaming body of a Request or Response.

Individual frames are streamed via the poll_frame function, which asynchronously yields instances of [Frame<Data>].

Frames can contain a data buffer of type Self::Data. Frames can also contain an optional set of trailers used to finalize the request/response exchange. This is mostly used when using the HTTP/2.0 protocol.

The size_hint function provides insight into the total number of bytes that will be streamed.

Associated Types

type Data: Buf;

Values yielded by the Body.

type Error;

The error type this Body might generate.

Required Methods

fn poll_frame(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Result<Frame<Self::Data>, Self::Error>>>

Attempt to pull out the next frame of this stream.

Return value

This function returns:

  • Poll::Pending if the next frame is not ready yet.
  • Poll::Ready(Some(Ok(frame))) when the next frame is available.
  • Poll::Ready(Some(Err(error))) when an error has been reached.
  • Poll::Ready(None) means that all of the frames in this stream have been returned, and that the end of the stream has been reached.

If Poll::Ready(Some(Err(error))) is returned, this body should be discarded.

Once the end of the stream is reached, implementations should continue to return Poll::Ready(None).

Provided Methods

fn is_end_stream(&self) -> bool

A hint that may return true when the end of stream has been reached.

An end of stream means that poll_frame will return None.

A return value of false does not guarantee that a value will be returned from poll_frame. Combinators or other implementations may not be able to know the end of stream has been reached for this hint.

Returning true allows consumers of this body to optimize, such as not calling poll_frame again.

fn size_hint(&self) -> SizeHint

A hint that returns the bounds on the remaining length of the stream.

When the exact remaining length of the stream is known, the upper bound will be set and will equal the lower bound.

Implementors