Collect and cache metadata, run hooks on changes.

Gerrit User 14985 afe48dff88 Update patch set 1 ... Patch Set 1: Code-Review+2 Patch-set: 1 Reviewer: Gerrit User 14985 <14985@4a232e18-c5a9-48ee-94c0-e04e7cca6543> Label: Code-Review=+2		2021-05-17 14:52:37 +00:00