Introduce a SnapshottingRefDirectory class which allows users to get
a snapshot of the ref database and use it in a request scope (for
example a Gerrit query) instead of having to re-read packed-refs
several times in a request.
This can potentially be further improved to avoid scanning/reading a
loose ref several times in a request. This would especially help
repeated lookups of a packed ref, where we check for the existence of
a loose ref each time.
Change-Id: I634b92877f819f8bf36a3b9586bbc1815108189a
Signed-off-by: Kaushik Lingarkar <quic_kaushikl@quicinc.com>
33c00f3347