Tracking bug for (1) object cache patches needing CR and (2) object cache tasks suitable for coding by someone from CPT that is new to that code base.

Tasks:

• T235705 Add BagOStuff metrics for read/write operations (bytes, key "class") grouped by type/ID
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/530019/
• T227376 Move callers away from getMainObjectStash() that do not need it
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/AbuseFilter/+/522619/
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/LoginNotify/+/529192/
  • https://gerrit.wikimedia.org/r/522619
• T235188 Preemptive refresh in getMultiWithSetCallback() and getMultiWithUnionSetCallback() pollutes cache
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/542961/ (should be done differently)
• T229062 Look into a simple way to have global keys with db-replicated
  • https://gerrit.wikimedia.org/r/524655
• T236412 Refactor BagOStuff to use a more storage/multi-DC aware interface hieararchy
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/524663/
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/529404/
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/531770/
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/529403/
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/529404/
• T228307 Create Default MainStash Solution
  • https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/525683/