645259 - Make preferences sync... sync

Status: NEW

(Firefox :: Sync, defect, P3)

Description

[Richard Newman [:rnewman]]

IRC:

rnewman: philikon: am I crazy, or does our prefs engine not so much "sync" as treat all prefs as a single record?

rnewman: from the looks of it, if you modify two different prefs on two different devices, whichever one syncs last has its change overwritten by the server record

philikon: rnewman: correct


This should be easy to verify:

* Create two profiles, synced
* Modify pref A on profile 1
* Modify pref B on profile 2
* Sync profile 1
* Sync profile 2.

Profile 2 will have pref B set to its value from profile 1 -- i.e., the local change will be undone.

If this is the case, it's an awful opportunity for bugs, particularly with our default fairly long sync intervals.

Comment 1

[Philipp von Weitershausen [:philikon]]

(In reply to comment #0)
> If this is the case, it's an awful opportunity for bugs, particularly with our
> default fairly long sync intervals.

The idea is that when one of the prefs in question changes, we bump the score to a ridiculous amount to immediately force a sync on idle. Of course, that won't have the other machines download the new setting any more quickly, but smaller Sync intervals should help here. I also think we need more flexible ways for an engine to do reconciliation. In this case, the prefs engine could easily reconcile changes if two separate prefs were changed.

Comment 3

[Richard Newman [:rnewman]]

I think this is pretty well demonstrated by, e.g., Bug 656151. And we ought to do Bug 582536, too.