On Mon, Nov 21, 2016 at 9:28 AM, Kit Cambridge <[email protected]> wrote:
> 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! > This is a really big deal. Great work rebuilding one of the cruftiest parts of Desktop Sync. This is how we get to a better world! Huge ups to the reviewers, too -- this would be hard to write, let alone swap in and juggle all the interactions... Nick
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