当我从本地C代码调用Rust dylib时会发生什么？

Question

Say, I have some dummy library written in Rust:

#![crate_type = "dylib"]

#[no_mangle]
pub extern "C" fn foo() {
    println!("bork!");
}

And I'm using it from C native code like that:

void foo();
int main()
{
    foo();
    return 0;
}

I'm particularly interested in two things:

• Does additional threads gets spawned on the Rust function call?

• How much blocking happen on such call - mutexes, locks, memory allocations on heap, anything like that.

I'm thinking of using Rust for real-time DSP applications and therefore I must be aware of any blocking operations that take place here. But I'm not enough hardcore to dig in actual C-Rust interop implementation myself..

Answer 1

Nothing special happens. Compiled Rust code that is exported with extern C looks just the same as any other native code.

Does additional threads gets spawned on the Rust function call?

No threads are created, unless your code creates them.

How much blocking happen on such call - mutexes, locks, memory allocations on heap, anything like that.

No, unless your code does such.