Android: Which response code does in-app billing V3 return upon timeout?

Solution 1:

I will describe my findings here. I have tested this on an AVD with a fully featured GP installed (GP Store V3.10.10, GP Services 2.0.12, G Services Framework 4.1.2), by pulling the host's plug.

• The getPurchases() method returns a cached result if possible (please note that we're not talking about a cache outside of the Service here but a direct call of getPurchases). Of course, this means that one will almost always get a cached result except when the Service is being re-initialized due to the loss of local data -- a case which is not very likely and often needs not be treated in special ways on the application level.
• The consumePurchase() method will return the integer value 6 (BILLING_RESPONSE_RESULT_ERROR) after a presumed internal net timeout of 20 seconds (so add a bit of time until the result code is seen by the caller). I was suspecting this despite BILLING_RESPONSE_RESULT_ERROR being described as a Fatal error during the API action because no other error code would make sense here; unfortunately, the word fatal is still somewhat inappropriate for a temporary condition such as a timeout.
• getSkuDetails() appears to behave just like consumePurchase(). Update: There's now evidence that getSkuDetails() can access cached information within the local service, too.
• It looks as if getBuyIntent() works fine without connectivity if the item is already known to the service. This explains why Hartok sees a blank GP purchase screen: It's not a problem to get a buy intent from the IAB V3 without connectivity.

Conclusion: The In-App Billing Service V3 appears to work with an internal cache and a server connection timeout of 20 seconds. For server communication errors which the local cache cannot resolve, response code 6 is used.