ISSUE#195 github.com/spf13/viper is not thread safe

[platsko]

There is a suggestion to solve the problem with the Viper package using wrapper functions. Let's discuss this.

[Sriep]

Looks promising. We need unit tests for core/viper. What about reading in various 0chain config files, writing them out then rereading them? Then checking it worked.

We also want to test concurrency, so maybe run several tests in parallel that modify the viper store, in a similar way to 0chain, and confirm it can cope.

[platsko]

@Sriep
During testing, significant shortcomings in the implementation were revealed, many methods cannot be thread-safe - I think it would be better to get rid of them altogether. Please see the last commit.

[Sriep]

Do we use any of the non-thread-safe methods? Yes AddConfigPath and SetConfigType.

Eye on the goal: We don't want race errors. So either avoid using unsafe viper methods or make sure they are only accessed from one thread.

[Sriep]

I think we just have to let the non-thread-safe methods stand. Assume they are always called safely.

We can then raise a separate issue to check our usage of non-thread-safe viper methods and, if necessary, fix that in a separate PR.

Done