tree 94da67ed97d3ddc2d66ffd74f4f50dcb34b0cc17
parent 67f0c672f2ec989e83c4d6d3f687cd28f5393db3
author Patrick Hiesel <hiesel@google.com> 1550563762 +0100
committer Patrick Hiesel <hiesel@google.com> 1553089953 +0100

Implement PureRevertCache

Computing if a change is a pure revert of another change or commit
is an expensive operation as it requires a Git merge. This is especially
true for large Git repositories.

However, this information is easy to cache in a persistent cache as it
can be keyed by the SHA1s of the commits that we want to diff. Given
that this computation runs many times if the Prolog fact is used because
we freshly compute the submit rules often, this commit builds a
persisted cache for it.

There are many existing tests that cover the behavior in ChangeIT.

This commit adds a serializer for Protobuf to ensure we are not using
the default Java serialization as well as a test.

Change-Id: Id79e2fb2f6646d8e48fdfc3a3b0bcf03f51b1400