Customer are interested in using OBSERVE functionality to allow them to check whether items have been replicated successfully, as they are worried about unreplicated items.
has basic info on the OBSERE functionality in libcouchbase, but we need to provide concrete examples on how to check multiple keys having been replicated successfully (they do a bulk write, so should be more efficient to wait for all of them, rather than wait for them individually)
Examples provided to the customer :
You will find the below example very useful for simple operations :
The below example would provide more insights when you have any performance or reliability issues :
The basic idea here is to constantly "poll" the keys (sleeping within a given interval) until all of them are declared as "OK". The structures involved are the "observe_expectation" (persistence/replication requirements), the "pollprefs" (i.e. timeout, interval, etc.) and the "keystate" - this keeps tabs on how the actual status of each key matches up with the specified criteria. The lcb_observe callback is called for each "status report" for each key from each server; so it is necessary to check and see if the requirements have been met during each individual update.