tree 98e66cb03af936cf1968d047ae4669752cd8ae53
parent b68eed02fe82893b481869502e3520e91b68939d
author Shawn Pearce <spearce@spearce.org> 1502565570 -0700
committer Shawn Pearce <spearce@spearce.org> 1503017398 -0700

dfs: reftable backed DfsRefDatabase

DfsReftableDatabase is a new alternative for DfsRefDatabase that
handles more operations for the implementor by delegating through
reftable. All reftable files are stored in sibling DfsObjDatabase
using PackExt.REFTABLE and PackSource.INSERT.

Its assumed the DfsObjDatabase periodically runs compactions and GCs
using DfsPackCompactor and DfsGarbageCollector.  Those passes are
essential to collapsing the stack of reftables.

Change-Id: Ia03196ff6fd9ae2d0623c3747cfa84357c6d0c79