tree a795e72e7df373434e3526777ce92841049e6601
parent df81c56524e578f569ea12854526c1461ac6e42d
author Ivan Frade <ifrade@google.com> 1585804209 -0700
committer Ivan Frade <ifrade@google.com> 1588117252 -0700

UploadPack: Extract walk-based reachability check

Preparing the code to optimize the bitmap-based object reachability
checker.  We are mirroring first the commit reachability checker
structure (interface + 2 implementations).

Move the walk-base reachability checker to its own class.

This class is public at the moment. Later ObjectWalk will return an
interface and this implementation will be package-private.

Change-Id: Ifac70094e1af137291c3607d95e689992f814b26
Signed-off-by: Ivan Frade <ifrade@google.com>