1380551 - Device list crashes the first time and won't send until sync is complete

Status: NEW

(Firefox for iOS :: Sync, defect)

Description

[Ryan Feeley [:rfeeley]]

Attachment: send-spinning.png

This is one to get right for our loyal users with large existing profiles.

STEPS TO REPRODUCE
1. Install Firefox for iOS Nightly fresh (I'm using iPhone SE)
2 On iOS sign into an existing account with a large profile (100 MB) and multiple devices
3. Before entire profile has synced, select Send Tab and select a device to send to

EXPECTED RESULTS
- Device names will with minimal delay
- User can send tab before all profile data has synced

ACTUAL RESULTS
- Device list crashes the first time Send Tab is selected
- The second time, before the Sync is complete, the device names loads, but the Send button is stuck on the spinner indefinitely (I’m assuming until the large profile is fully synced)

Comment 1

[Richard Newman [:rnewman]]

We download client records at the start of a sync, so they should already be in the database mere moments after the login is first verified.

That means there are two potential bugs here:

1. You try to share a tab while a sync is in progress, but before `clients` has synced. It would be nice to have a `Deferred` to chain off for this specific collection, because we can't do anything until it finishes, and it should finish quickly.

2. You try to share a tab while a sync is in progress, but after `clients` has synced.

In the latter case, the device list picker *should* use the existing list, then attempt to re-fetch. The re-fetch attempt should fail, because a sync is in progress, or it should return the `Deferred` for the long sync and we shouldn't block on it.

Fixing this bug is a little bit fiddly, and involves a reasonable understanding of `Deferred`.

I wonder if that initial crash is a different bug -- I sometimes get an initial crash followed by data loss.