Maniphest T211914

WinCache increment loses TTL information
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Description

Symptoms
When incrementing the value of a key, using $cache->incr($key);, the key is reset with an infinite Time To Live (0 in WinCache). This violates the expectation that the increment function preserves TTL.

Results
Throttling is broken because the throttle keys do not expire when they should. As a user performs more actions, they begin accumulating indefinitely, so the user is throttled until the WinCache is manually cleared.

Fix
Reimplement the increment function for WinCache, taking into account the right TTL.

Details

	Subject	Repo	Branch	Lines +/-
	objectcache: Fixes WinCache increment losing TTL.	mediawiki/core	master	+23 -0

Customize query in gerrit

Event Timeline

osorio-juan-microsoft created this task.Dec 13 2018, 7:12 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptDec 13 2018, 7:12 PM

Change 479513 had a related patch set uploaded (by Juan Osorio (Microsoft); owner: Juan Osorio (Microsoft)):
[mediawiki/core@master] Fixes WinCache increment losing TTL.

https://gerrit.wikimedia.org/r/479513

gerritbot added a project: Patch-For-Review.Dec 13 2018, 7:32 PM

osorio-juan-microsoft moved this task from General to libs/objectcache on the MediaWiki-libs-BagOStuff board.Jan 11 2019, 11:31 PM

osorio-juan-microsoft triaged this task as Medium priority.Jan 22 2019, 5:58 PM

@Krinkle Do you think you could help me take a look at this one?

@osorio-juan-microsoft Thanks for patching this. That looks like a pretty bad problem indeed. Sorry about that.

I have made changes to this class as part of wider maintenance work, but unfortunately don't have any knowledge about WinCache, nor am I presently able to verify or test this.

I've tagged Platform Engineering who might want to take a look at this first.

CCicalese_WMF edited projects, added Platform Engineering (Needs Cleaning - Security, stability, performance, and scalability (TEC1)), Platform Team Workboards (Waiting for Review); removed Platform Engineering.Feb 5 2019, 3:13 PM

Change 479513 merged by jenkins-bot:
[mediawiki/core@master] objectcache: Fixes WinCache increment losing TTL.

https://gerrit.wikimedia.org/r/479513

ReleaseTaggerBot added a project: MW-1.33-notes (1.33.0-wmf.17; 2019-02-12).Feb 6 2019, 1:01 AM

Krinkle closed this task as Resolved.Feb 6 2019, 2:45 AM

Krinkle removed a project: Patch-For-Review.

CCicalese_WMF moved this task from Waiting for Review to Done with CPT on the Platform Team Workboards board.Feb 8 2019, 2:49 PM

CCicalese_WMF edited projects, added Platform Team Workboards (Done with CPT); removed Platform Team Workboards (Waiting for Review).