外部功能：谁释放内存？

Question

I'm calling a Go function from Python. Go function returns a string, specifically, a GoString with the string itself being allocated on Go's side.

Question

Who's responsible for deallocation of this memory?

---

A very simplified example follows.

Go side:

func Create(optsEncoded string) (res string, serr string) {
    opts := map[string]interface{}{}
    if err := json.Unmarshal([]byte(optsEncoded), &opts); err != nil {
        return "", errWithStack(err)
    }
    options := translateCreateOptions(opts)

    result := ...

    payload, err := json.Marshal(result)
    if err != nil {
        return "", errWithStack(err)
    }
    return string(payload), ""
}

Cython bindings:

cpdef object py_create(object items, bytes options):
    cdef GoString opts = ...
    cdef bytes message

    cdef Create_return result = Create(opts)

    if result.r0.n == 0:
        message = result.r1.p
        raise Exception("Something happened")
    message = result.r0.p
    # Do I need to deallocate result.r0 and result.r1?
    return message.decode("utf-8")

Answer 1

I don't think you should return a GoString to C. Since the memory of GoString is managed by the go runtime and will be garbage collected. It's unreliable in C land to use this string. What you should do is return a CString by calling cs := C.CString(s). Memory allocations made by C code are not known to Go's memory manager. So I think its up to you to mange which side to free the CString, here and here.