Hi all, Tomorrow's Nightly will include some improvements to how we track bookmark changes for syncing [1]. I wanted to take some time to summarize them in this email.
Previously, Sync listened for observer notifications from Places [2], recorded the changes in memory, and periodically flushed them to disk. This caused Sync to occasionally miss changes at startup or during a sync, and lose changes from interrupted syncs. The fix moves the change tracking logic into Places. Instead of using observers, the new bookmarks tracker pulls the set of changed bookmarks directly from the database. A new "change counter" column increments every time a bookmark is modified in a way that should trigger a sync, and decrements once the bookmark has been successfully uploaded to the server. The counter is updated in a transaction, ensuring we don't lose changes at startup or shutdown. This design also avoids missing changes during a sync. We think these lost changes are responsible for a large portion of corrupt server bookmark trees. This corruption can spread to other devices, and blocks us from enabling bidirectional syncing on iOS. We've developed a two-pronged mitigation strategy: prevent Sync from corrupting the server in the first place, and repair existing corruption by uploading missing bookmarks. The tracker improvements are a form of prevention, and repair is currently in the works [3]. If you're using Sync, I encourage you to install the About Sync add-on [4], and validate your bookmarks [5]. We want to make sure the new tracker doesn't introduce new errors. If you've been using Sync for a while, it's likely you'll already have some validation errors. We want to know about these, too, so that we can prioritize our repair efforts. Please file new bugs in the "Firefox :: Sync" component on Bugzilla, or reply to this thread. Special thanks to Marco Bonardo, Mark Hammond, Richard Newman, and Thom Chiovoloni for all their insightful feedback and reviews! Cheers, - kit [1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1258127 [2]: Places is the system that manages bookmarks and history in Firefox. [3]: https://bugzilla.mozilla.org/show_bug.cgi?id=1317223 [4]: https://github.com/mhammond/aboutsync, https://addons.mozilla.org/en-US/firefox/addon/about-sync/ [5]: Once you've installed the add-on, go to Tools > About Sync, and click the "Validation" tab under the "bookmarks" collection. _______________________________________________ Sync-dev mailing list Sync-dev@mozilla.org https://mail.mozilla.org/listinfo/sync-dev
