1159860 - Stop generating parent diffs for every commit

Status: RESOLVED FIXED

(MozReview Graveyard :: General, defect)

Description

[Steven MacLeod [:smacleod]]

Currently for each commit after the base commit we generate two diffs and upload them to Review Board - a "diff" and a "parent diff". Review Board first applies the parent diff to give us the base for the commit, and then the diff is displayed on top of that.

Each of these commit review requests all point at the same base revision, and then include in their parent diff all commits that come before them in the push. This causes the parent diff to be larger for each successive commit.

The reason this was done is so that Review Board could point at the mainline repository (such as a mozilla-central). The mainline doesn't know of the commits up for review meaning Review Board could not use a non-mainline commit as the base for a commit review request.

In practice we've been pointing Review Board at the review repos themselves rather than the mainline meaning all these parent diffs are wasting space (and CPU resources being applied).

We should stop generating and uploading these parent diffs, instead just providing the proper base commit and a single diff for each commit. This also means mandating that Review Board must remain pointed at the review repo and not mainline going forward.

Comment 1

[Steven MacLeod [:smacleod]]

Attachment: MozReview Request: bz://1159860/smacleod

/r/8179 - MozReview: Allow specifying base_commit_id and make parent_diff optional (Bug 1159860). r?gps
/r/8181 - MozReview: Stop generating parent diffs (Bug 1159860); r?gps

Pull down these commits:

hg pull -r 158efe0c2b26977522c4803007414de0b95b4a74 https://reviewboard-hg.mozilla.org/version-control-tools/

Comment 2

[Gregory Szorc [:gps]]

https://reviewboard.mozilla.org/r/8179/#review6943

Ship It!

Comment 3

[Gregory Szorc [:gps]]

https://reviewboard.mozilla.org/r/8181/#review6945

Ship It!

Comment 4

[Gregory Szorc [:gps]]

Comment on attachment 8601762 [details]
MozReview Request: bz://1159860/smacleod

https://reviewboard.mozilla.org/r/8177/#review6947

This all seems sensible to me given what we talked about last week and what's said in the commit messages.

Let's be sure to test this on dev before it is pushed to prod. I have a nice long commit series we can use to benchmark this. I'm excited about the reduced computation at push time! I'm already a bit concerned about push performance and it's good to see us going in the right direction.

Comment 5

[Steven MacLeod [:smacleod]]

Pushed https://hg.mozilla.org/hgcustom/version-control-tools/rev/bbf29965c039

Comment 7

[Steven MacLeod [:smacleod]]

Attachment: MozReview Request: MozReview: Allow specifying base_commit_id and make parent_diff optional (Bug 1159860). r?gps

Comment 8

[Steven MacLeod [:smacleod]]

Attachment: MozReview Request: MozReview: Stop generating parent diffs (Bug 1159860); r?gps