Collect and cache metadata, run hooks on changes.

Gerrit User 7144 a5267d569a Update patch set 2 ... Patch Set 2: Code-Review+2 Patch-set: 2 Reviewer: Gerrit User 7144 <7144@4a232e18-c5a9-48ee-94c0-e04e7cca6543> Label: Code-Review=+2		2021-04-13 12:51:31 +00:00