tree 47fc676be6db75ff5f878e3e27f14daa1547fa4e
parent 7da2fe6be88cb6696b4d3e59189298daa2a2816a
author Shawn Pearce <spearce@spearce.org> 1499967864 -0700
committer Shawn Pearce <spearce@spearce.org> 1503007611 -0700

reftable: merge-join reftables

MergedReftable combines multiple reference tables together in a stack,
allowing higher/later tables to shadow earlier/lower tables.  This
forms the basis of a transaction system, where each transaction writes
a new reftable containing only the modified references, and readers
perform a merge on the fly to get the latest value.

Change-Id: Ic2cb750141e8c61a8b2726b2eb95195acb6ddc83