Offline Mode Queries Hang for Minutes

[barrysohl]

We use Plugin.CloudFirestore extensively throughout our large XF app on both iOS and Android. Overall, we have had great success with the plugin. However, offline mode seems to be badly broken.

• Queries that take less than a second on WiFi can take several minutes when offline!!
• These are small queries, less than 25 small documents each.
• Several queries have the same problem, so it is not just one.
• The behavior is the same on both iOS and Android.
• The queries do eventually come back with correct data though!
• We do not have this problem accessing Firestore from a native app, so we are fairly sure it is plugin related.
• Plugin.CloudFirestore version 3.1.0
• XF version 4.7.0

Any ideas? Please help! This is an absolute showstopper for us.

[barrysohl]

Turns out forcing 'source' to Cache when offline fixes the issue entirely! After scouring online, it looks like Firestore always tries the network first, waits for a timeout (10sec?), then tries cache. If you have a number of queries to perform, this can means minutes of hang time. Google should really document this better somewhere.