Aurora.3/rust/bapi

What is this

todo

What is this _ffi stuff

FFI means "foreign function interface". Basically, different programming languages have very different features and mechanisms, and if we want them to communicate, like here DM and Rust, in a way, we need to go to the lowest level possible, that being C, as that is what basically every language can understand.

Rust functions callable from DM should end with _ffi, and have a very "raw" form, and do the least things possible to just call the actual Rust functions.

Rust functions that do actual things should not end with _ffi, and can be nice, idiomatic, Rust-like, and most importantly, safe.

On safety

I recommend reading up on these topics related to Rust: safety, unsafe {}, error-handling, panics.

Safety related stuff:

• Generally, try to call stack trace dm proc on error or panic, so it fails tests and stops debugging (may need to turn on breakpoints on runtime errors).
• Panics (like foo().unwrap();) are caught with a panic handler that calls stack trace proc, and writes to a file. Panics are unrecoverable, so this is the best we can do in this case. Panics should not really happen though, except in a "fatal error and literally cannot proceed further" situation.
• Unhandled errors (like foo()?;) call stack trace proc and return null from the function. Errors should be propagated up, using the eyre library, with every function returning eyre::Result<T>.
• Some unsafety may be required, like to parse args in _ffi functions, but should not be present any where else. And if for whatever reason it is needed, it should be documented well.
• All rust code (generally, outside of _ffi) should be nice, safe, and idiomatic.

Compiling and testing

Command to compile bapi. The resulting .dll should be in ./rust/bapi/target/i686-pc-windows-msvc/release/.... The server should try to find and use the .dll in that location, otherwise use ./bapi.dll in main dir. Building either in release mode (with optimizations) or in debug (without, the default) is fine, but release .dll takes priority.

cargo build --target=i686-pc-windows-msvc
cargo build --release --target=i686-pc-windows-msvc