_changes stop working in iOS 10

[pasin]

The issue originated from couchbase/couchbase-lite-ios#1477.

I believe it's the issue is caused by either the HTTP Client or iOS WebKit. We should do some testing on this.

[msanilkumar2020]

Any update on this issue?

We are not getting _changes in iOS.

Thanks,
Anil Kumar

[pasin]

Sorry, we don't have any update. Can you post exact the _changes request including all parameters that you are using? What is the HTTP client you are using to make _changes request in the application?

[Crapulax]

To provide a bit more information, we workarounded the issue by:

• setting a _changes heartbeat* to 20s (20000). Using a timeout of 40s at the http level was also working.
• reinitializing the listen when app move from background to foreground
  Note that resume reinialization was tricky because we had to know if the issue had occured or not. We determine this by keeping last sequence received by _changes and comparing it with update_seq from DB. If they are equal we loop on it in case it is down.

Above is not satisfactory as it requires tricky computations.

*heartbeat: edited (wronly wrote timeout)

[pasin]

I believe a better approach would be adding heartbeat=30000 to the longpoll _changes feed request URL. Another option would be adding timeout to _changes feed request BUT currently couchbase-lite-ios doesn't support _changes feed timeout yet (See couchbase/couchbase-lite-ios#1236).

FYI, we did experience that some HTTP clients do not abort the requests properly after timing out so the requests get stuck and have never returned the result (See https://github.com/couchbase/couchbase-lite-java-core/issues/1296 for more info).

[Crapulax]

Sorry Pasin, I wrongly wrote timeout, we should read heartbeat instead. I update my post accordingly.

I am checking right now if using a promise as timeout can let us remove the tricky stuff on app resume

[pasin]

@Crapulax Thanks for the update.