Re: [PATCHv2 1/2] attr: convert to new threadsafe API

> Stefan Beller <sbeller@google.com> writes:
>
>>  extern struct git_attr *git_attr(const char *);
>> ...
>> +extern void git_attr_check_append(struct git_attr_check *,
>> +                               const struct git_attr *);
>
> Another thing.  Do we still need to expose git_attr() to the outside
> callers?  If we change git_attr_check_append() to take "const char *"
> as its second parameter, can we retire it from the public interface?
>
> It being an "intern" function, by definition it is not thread-safe.
> Its use from prepare_attr_stack() inside git_check_attr() that takes
> the Big Attribute Subsystem Lock is safe, but the callers that do
>
>         struct git_attr_check *check = ...;
>         struct git_attr *text_attr = git_attr("text");
>
>         git_attr_check_append(check, text_attr);
>
> would risk racing to register the same entry to the "all the
> attributes in the known universe" table.
>
> If the attribute API does not have to expose git_attr(const char *)
> to the external callers at all, that would be ideal.  Otherwise, we
> would need to rename the current git_attr() that is used internally
> under the Big Lock to
>
>     static struct git_attr *git_attr_locked(const char*)
>
> that is defined inside attr.c, and then provide the external version
> as a thin wrapper that calls it under the Big Lock.
>
>