Re: reftable [v4]: new ref storage format

On Sun, Jul 30, 2017 at 11:51 PM, Shawn Pearce [off-list ref] wrote:

- Near constant time verification a SHA-1 is referred to by at least
  one reference (for allow-tip-sha1-in-want).

I think I understated the importance of this when I originally brought
up allow-tip-sha1-in-want. This is an important optimization for *any*
HTTP server, even without allow-tip-sha1-in-want, in order to validate
the SHA-1s sent in the upload-pack request, which doesn't share memory
state with the /info/refs request processing.