Do not attempt to sync when there is not Internet

[mnalis]

I have mobile data turned off for most of the time (expensive data plan), and WiFi availability is spotty.

ICSx5 2.4.2 (and previous versions) on my Android 15 however seems to want to sync automatically even when no network (neither mobile data nor WiFi) is available, and thus annoying often produces lots of notifications (one for each ICS feed) about being

unable to resolve host "x.y.example.com": No address associated with hostname

That gets quite annoying after some time, and wastes user time. Of course when there is no Internet then you wouldn't actually be able to sync with internet hosts (nor resolve their names), doh.

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Suggestion: can it be made so if there is no Internet connection available, ICSx5 does not even attempt to sync automatically with network hosts?

Related previous discussions: #103 and especially #45 which seems to indicate that is already being attempted, but apparently not working (that is about 3.5 years old, and lots of things in android have changed; perhaps there is better way now to check?)

I am having Rethink VPN enabled all the time (regardless if there is internet present at the moment or not), if that might be related data point.

DAVx5, Nextcloud etc. seem to detect lack of internet and do not try to sync when it is not present.

P.S. thanks for that nice piece of FOSS, other then this things it works perfectly for me!

[ArnyminerZ]

Hi, ICSx⁵ is supposed to be running only when there's Internet connectivity. However, this information is given by Android automatically, and honestly, it's not very good. On DAVx⁵ we have workarounds, but it's still an issue. ICSx⁵ simply doesn't have those things implemented.

I am having Rething VPN enabled all the time (regardless if there is internet present at the moment or not), if that might be related data point.

Yes, it might be. VPNs really mess up what Android considers a "valid connection".

[sunkup]

Adding this here for context: bitfireAT/davx5-ose#990 (comment)

[sunkup]

Suggestion: can it be made so if there is no Internet connection available, ICSx5 does not even attempt to sync automatically with network hosts?

Like @ArnyminerZ says we rely on android here and it even differs between android versions what kind of information is available and when they will "wake up" ICSx5 to do its syncing. This is smart because it uses less battery.

So an idea which often comes up is to add an option to simply not require validated internet, always wake up from sleep and do the connectivity check ourselves before attempting to sync. If we make it a user setting we could add a warning about the increased battery drain.

Another idea could be to add an option which disables showing notifcations on missing internet connection. It should then probably still fail the work run, so it is retried after some time. I am worried however, that this might spark more problems than it solves.

In any case we should analyse the problem in depth and think of the best / least damaging solution before implementing something.

I hope you see that it's not an easy fix @mnalis

[mnalis]

Thanks for details, @sunkup !

While I understand that always-on VPN could make things more difficult to detect, I'll note that none of the other FOSS apps (including those which sync periodically display on their own like ICSx5) have that problem in the same situation, which gives me hope it could be improved.

That includes DAVx5 (I've never got such spurious error about being unable to connect), but also NextCloud client (which properly displays "No internet connection" and does not attempt to sync when e.g. VPN is on but wifi&data off) and StreetComplete (which says "You are offline" if I attempt to sync while wifi and data are off). So perhaps similar measures could be employed by ICSx5 too? I see two main ways to do it:

• when woken up for sync, check if Internet is present. If it isn't, do not attempt sync which will fail, but defer the sync instead for another time; or
• when woken up for sync, attempt syncing just like it does currently, but if sync fails with error, check if the Internet is present. If it isn't present, skip generating notification errors, as they are spurious.

Would one of those be possible?

[ArnyminerZ]

That includes DAVx5

With DAVx⁵ we ship more complex checks that avoid these kind of issues (though there are some). It's simply very very hard to check whether you actually have a proper Internet connection. For example, we could even check manually for Internet connectivity before syncing (by pinging the server for example), but if your signal is weak, Internet connection is slow or spotty... Errors may always occur.

Android's system, in general, is always also very confused sometimes on what a valid network is.

[8rror404]

What about the possibility of an option to only sync over Wi-Fi - ie when connected to a Wi-Fi network?

Would this be an easier option?

It would suit my user case scenario and may go towards a solution for the original user (and others) - although I accept in their case WiFi availability is spotty

[ArnyminerZ]

Well, technically we can add a simple switch to only sync when "connected to an unmetered network". However, being connected to a WiFi network doesn't always guarantee Internet access, even a router just connected to a plug, without any access to the Internet may say that the WiFi network is unmetered, so we would be having the same issue.

[mnalis]

Well, technically we can add a simple switch to only sync when "connected to an unmetered network"

Adding such switch would actually work nicely for me too! (at least in vast majority of the cases, if not absolutely always).

(And it would additionally help with keeping mobile data costs down for people who pay for traffic)

So, could we have such switch?

being connected to a WiFi network doesn't always guarantee Internet access, even a router just connected to a plug, without any access to the Internet may say that the WiFi network is unmetered

Sure, but such misconfigured/broken router is in fact a situation where one would want to continue getting those error messages (just like the user would still like seeing those errors if router itself is OK, and connected properly to ISP, but ISP is having problems with their own backbone connections or having other routing problems - displaying errors is not only fine, but expected in such cases).

On the other hand, user having intentionally manually disabled wifi/data would not need/want seeing such "unable to connect" errors, as "no internet connection" is obviously exactly what they wanted when they disabled it.

[ArnyminerZ]

Sure, but such misconfigured/broken router is in fact a situation where one would want to continue getting those error messages

Well, it can happen (and is common) that you connect to a public network, or a network of a hotel/apartment/campsite that doesn't have good connection/at all; or that it has a limited data plan or something.

I just want to convey that it's never that easy.

However, whatever the case, we will have an internal talk on this topic. We don't want to clutter the UI even more than it's right now, and it's on our roadmap to redesign the app from the ground up at some point.