Hi all,
I'm in the process of building a 
small application that utilises Jack in order to interface with audio 
hardware. Specifically, although this detail is only partially relevant,
 I'm writing it in Rust (using some community FFI bindings).
I
 was wondering what the thread safety guarantees of calling the 
processing callback are. Specifically, I was wondering if it can be 
guaranteed that the callback will only be called on a single thread at 
any given time?
This is primarily because it 
determines whether or not it is required for the callback to be marked 
as "Sync" in Rust - which would indicate that the callback's data must 
be thread safe, a restriction I'd prefer to avoid.
Thanks in advance.