726054 - Desktop parity: track last sync time from final upload, not final fetch

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: Android Sync, defect, P1)

Description

[Richard Newman [:rnewman]]

Desktop Firefox downloads records, bumping the last sync time from a record high-watermark, and then -- if an upload occurs -- bumps to the response X-Weave-Timestamp.

This, of course, is a race condition: if anyone else uploads records between starting our fetch and finishing our upload, we won't see them.

But it does avoid the problem of uploading a record and downloading it again on the next sync. So let's do this until we have sessions.

Comment 1

[Richard Newman [:rnewman]]

Perhaps a compromise would be to track two lastSync times, and fetch from the earlier timestamp if info/collections reports a later time than our last upload?

Comment 2

[Richard Newman [:rnewman]]

The alternative is to cross-session track, perhaps by querying on ID before we fetch. All nasty. Sync isn't really designed for this whole "syncing" malarkey.

Comment 3

[Richard Newman [:rnewman]]

https://github.com/mozilla-services/android-sync/commit/83dd5913e7ac8b72c5854e6fd002b8e6a62e6089

Comment 4

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/127239d2fdb5