Thread-safety when wrapping unmanaged code

Question

Using an API wrapper that contains functions like this

  [DllImport("someapi.dll", EntryPoint = "API_Func")]
        public static extern uint ApiFunc(string name);

Do I need to use a Mutex if the API itself is thread-safe? I'd say no.

Aside from functions there are just a few static const ints and a few struct declarations. So on the managed side there shouldn't be any thread-shared resource right?

Answer 1

Thats a question which really made me think...

My understanding

Since the functions are declared as static extern, the functions are not associated with any instance of a class, and there are no instance variables that could be shared among different threads, which could lead to potential race conditions.

As you mentioned, aside from functions, there are just a few static const ints and a few struct declarations. Since the consts and structs are not shared resources, there shouldn't be any issues with thread-shared resources on the managed side. The consts are read-only and cannot be modified, so there's no risk of race conditions when accessing them from multiple threads.

TL;DR

If the API documentation states that it is thread-safe, you can rely on the API to manage thread synchronization internally. In that case, I agree with you, you don't need to use a Mutex on the managed side.