tokio-rustls: how to use buffering with TlsStream? about tls HOT 4 OPEN

poll_write calls the underlying poll_write every time.

I don't think this is correct, it only calls poll_write when it satisfies wants_write.

from tls.

My interpretation was that wants_write returns true always if there is something to write at all.

    pub fn wants_write(&self) -> bool {
        !self.sendable_tls.is_empty()
    }

from tls.

You seem to be right. given that rustls has a flush method, this seems to be a reserved behavior for rustls.

There are two buffer in write direction, one is sendable_plaintext before send and one is sendable_tls after send.
The sendable_plaintext is equivalent to BufWriter<TlsStream<TcpStream>>, and sendable_tls is equivalent to TlsStream<BufWriter<TcpStream>>.

Does rustls have any plan to expose write buffer? @ctz @djc

from tls.

We have a plan to have an unbuffered/write-through API, where rustls doesn't maintain any buffers for the data path. I've made some progress on this over the past year, but the next step is non-trivial to implement.

from tls.