Is this project abandoned?

[calvin2021y]

No description provided.

[roydahan]

No.
However, we soon would start promoting this one https://github.com/scylladb/cpp-rust-driver as a better alternative.

[calvin2021y]

Is cpp-rust-driver able to generate async c api like this project ?

[Lorak-mmk]

It is intended as a drop-in replacement - although not all functions are implemented.
If by "async c api" you mean functions like

cass_session_execute
cass_future_error_code
cass_future_set_callback
cass_future_free

and other methods from https://cpp-driver.docs.scylladb.com/master/api/struct.CassFuture.html , then yes, async API is implemented.