commit 4a43425ed02af7554a9fd01393711403f4d89f22
author Edwin Kempin <ekempin@google.com> Thu Mar 25 14:32:58 2021 +0100
committer Edwin Kempin <ekempin@google.com> Wed Mar 31 14:57:24 2021 +0200
tree dd613bc94c6d80ca1b2a34fb291cc1e9a485a35e
parent 6bc25fa98e82327dd2f1fd54ecb4af7bb9d6e93c

Do not invoke submit rules twice when updating a change

Currently the submit rules are executed twice whenever a change gets
updated, once for indexing the change, and once for sending out the
change-updated event (both of these code paths create a ChangeData
instance and the submit rules get triggered when certain fields in
ChangeData are accessed for the first time).

Executing the submit rules twice is bad as the execution time for the
submit rules adds up to the latency of the update request, and running
some submit rules (e.g. the code owners submit rule) is rather
expensive.

Change I415d745de caches the ChangeData instance that is created for
indexing the change and makes it available in the postUpdate phase. We
now reuse this ChangeData instance to send out the change-updated event.
Since this ChangeData instance has the results of the submit rules
already cached, the submit rules are not triggered again.

By re-using the ChangeData instance we potentially also avoid doing
other expensive lazy loads twice (EventUtil already avoids this for some
expensive options by skipping them when formatting the change JSON for
the change events, with this change doing this may become unnecessary).

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Iad5f9f2294983087918beceab327dc28eb24deef