If you already know the length of a const char*, but that const char* doesn't happen to be a string literal, there is currently no way to construct a StringData object that captures both the string pointer and the known length without an additional call to strlen. Adding an new constructor that takes a const char* and a length would fix this.

I have a patch for this in progress and I will post a github pull request with the fix later today, so feel free to assign it to me, or to Alberto if that is not possible.