tree fea8606536d105806b9be3f7617b8aca42596861
parent da7671fcd5593431c9a31c9e005565217b44fe10
author Shawn Pearce <spearce@spearce.org> 1500468091 -0700
committer Shawn Pearce <spearce@spearce.org> 1500468315 -0700

dfs: Shrink DfsPackDescription.sizeMap storage

Using a HashMap is overkill for this storage.  PackExt is a
constrained type that permits no more than 32 unique values in the JVM.
Each is assigned a unique index (getPosition), which can be used as
indexes in a simple long[].

Change-Id: Ib8e3b2db15d3fde28989b6f4b9897f8a7bb36f3b