Make TlsStream cloneable

[NyxCode]

async_std::net::TcpStream implements Clone, which makes it possible to read and write to a socket at the same time.
Official async-std example
This library does not implement Clone for TlsStream, neither does it implement AsyncRead or AsyncWrite for &TlsStream.
How would I rewrite the example above to use TLS when TlsStream is not clonable?

[abhishekc-sharma]

@yoshuawuyts Correct me if I'm wrong but one of the changes suggested by @NyxCode above would need to be implemented to apply either of the solutions suggested in http-rs/async-h1#74

[garbage-repo]

I'm making a simple proxy server. So being able to read/write a TlsStream in 2 separate threads is a must.

If people are still interested in this, there's a unsafe work-around:

• Lets say you have a TlsStream, and call it reader.
• Use ptr::read() to make a copy of reader, name it writer.
• Use ManuallyDrop to wrap both reader and writer.
• Send them out to 2 threads.
• When done, call ManuallyDrop::drop() on one (and only one) of them.

Tests worked for me. My code is not in production yet. But this is the only hack for me. I hope this helps someone else.

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In long term, I hope crate authors could provide some split() function, which splits a TlsStream into 2 parts: one readable-only, one writable-only. I'm sorry that I don't have much knowledge about underlying TLS limits, but I hope that can be safely implemented. As I understand this: those 2 parts do not conflict.

--- Edited ---

I'm sorry it didn't work.