Backing type of Payload

[Ruttie2006]

Can a Payload struct's Bytes field be easily converted to BytesMut?
Or does that require copying?
In other words, is the Bytes field an exclusive that can simply be cast, or does it require a new allocation with values?

[vilgotf]

Bytes::from (otherwise accessible through Payload::from) is documented as:

If `bytes` is unique for the entire original buffer, this will return a
`BytesMut` with the contents of `bytes` without copying.
If `bytes` is not unique for the entire original buffer, this will make
a copy of `bytes` subset of the original buffer in a new `BytesMut`.

[Ruttie2006]

Yes, but my question is: when data is received from a websocket connection, is the bytes unique?

[vilgotf]

It will be unique unless required otherwise.
Currently that means it will be for data messages, but ping and close messages may be echoed by tws. However, frame masking makes it unique once again since it requires transforming the payload copy into BytesMut.

[Ruttie2006]

Are buffers re-used?
Or are they simply passed to the user and then dropped?

[vilgotf]

Decoded frames are split off from a BytesMut, which reclaims dropped chunks' capacity, and multi-frame messages are concatenated into unique buffers.