get_property: early return when property not found

[eguzki]

When property is not found, the testing framework was returning Status::Ok with empty array.

Proxy-wasm-sdk library is reading that as correct return value and returning Ok(Some(Bytes)). The correct branch should be Status::NotFound => Ok(None), when the property is not found. So, fixing the return value from the testing framework.
Here https://github.com/proxy-wasm/proxy-wasm-rust-sdk/blob/v0.2.1/src/hostcalls.rs#L396-L422

pub fn get_property(path: Vec<&str>) -> Result<Option<Bytes>, Status> {
    let serialized_path = utils::serialize_property_path(path);
    let mut return_data: *mut u8 = null_mut();
    let mut return_size: usize = 0;
    unsafe {
        match proxy_get_property(
            serialized_path.as_ptr(),
            serialized_path.len(),
            &mut return_data,
            &mut return_size,
        ) {
            Status::Ok => {
                if !return_data.is_null() {
                    Ok(Some(Vec::from_raw_parts(
                        return_data,
                        return_size,
                        return_size,
                    )))
                } else {
                    Ok(None)
                }
            }
            Status::NotFound => Ok(None),
            status => panic!("unexpected status: {}", status as u32),
        }
    }
}

[eguzki]

get_expect_get_property(path_raw) is setting status, so it must be asserted before returning.

[alexsnaps]

👍 Nice. Sort of unrelated, but I'm thinking the SDK is wrong in not differentiating between a nil value to an existing property and a non existent prop... I was thinking of raising that with them, as the fn sig is Err = Status, it could return that information rather than discarding of it.

[eguzki]

👍 Nice. Sort of unrelated, but I'm thinking the SDK is wrong in not differentiating between a nil value to an existing property and a non existent prop... I was thinking of raising that with them, as the fn sig is Err = Status, it could return that information rather than discarding of it.

I wonder what the meaning of nil is when you set a property and whether it has a use case or not.

[eguzki]

tested in Kuadrant/wasm-shim#39

[alexsnaps]

While String & Numbers are send as is, the byte[] is pretty much expected to be protobuf, so that there is no null and None as such is "there is no such property known"
That's my current understanding at least