Function splinter_poll 

pub unsafe extern "C" fn splinter_poll(
    key: *const c_char,
    timeout_ms: u64,
) -> c_int

@brief Waits for a key’s value to be changed. @param key The key to monitor for changes. @param timeout_ms The maximum time to wait in milliseconds. @return 0 if the value changed, -1 on timeout or if the key doesn’t exist.