Re: [PATCH] upload-pack: add tracing for fetches

> Generating the json output isn't entirely trivial (and certainly
> involves allocations), but we throw it away unused if tracing isn't
> enabled. Maybe we'd want something like:
>
>   if (!trace2_is_enabled())
>           return;
>
> at the top of the function? It looks like other callers of
> jw_object_begin() have a similar issue, and this is probably premature
> optimization to some degree. It just feels like it should be easy for
> tracing to be zero-cost (beyond a single conditional) when it's
> disabled.