Send+Sync for connection

[acasajus]

Looking at the docs it says that Send and Sync are not implemented for connection but in your r2d2-odbc crate it is "unsafely" implemented. Can they be implemented in this crate? Or do you allow it under r2d2 because it takes care not to share a connection amongst two threads?

[Koka]

Hello, thanks for your question. This needs more deep investigation because it's highly dependent on ODBC driver manager and driver itself whether it's safe to use things concurrently or not. r2d2-odbc is hacky quick'n'dirty implementation, but in this crate we try to do things more safely

[pacman82]

Just a quick comment from the sideline: In general it is unsafe, because it depends on your ODBC configuration wether this is safe or not. I'd suggest to promote a connection without Send + Sync to a connection type with Send + Sync via an unsafe function.

I think the relevant configuration to look at wether this is actually safe, is the threading level. See:
https://stackoverflow.com/questions/4207458/using-unixodbc-in-a-multithreaded-concurrent-setting#4207474

Threading=2 should be fine.

[bbigras]

I'm also interested in this. I would love to be able to use this crate with deadpool:
deadpool-rs/deadpool#43

I wouldn't mind using bb8 too.

[Koka]

Would gladly merge PR implementing the @pacman82 idea.