Data file corruption in VanillaChronicle

[brasslock]

Hi,

I have discovered an issue that causes corruption in VanillaChronicle.
Occasionally an existing data file is overwritten, so that earlier indexes that refer to the existing data file become invalid (length value is corrupt).

I believe that I have tracked the issue down to use of VanillaDataCache in VanillaChronicle. dataCache is an instance in VanillaChronicle, but it is shared across all appender instances. This means that VanillaDataCache.dataForLast can be invoked by multiple concurrent threads, resulting in inconsistent values for lastCount.

I will attempt to create a test case that illustrates the problem.

Thanks,
Ross

[brasslock]

Created a pull request in #78.
Closing this issue