`writeToCacheAsynchronously` consistency + synchronous memory cache / asynchronous disk cache

[BoD]

Currently, when writeToCacheAsynchronously is set to true, there are no mechanisms in place to ensure consistency: a read happening after a (async) write can return the state as it was before the write.

Also, writeToCacheAsynchronously is used at the CacheManager level and will apply no matter which cache implementation (memory/disk/both) is used.

It would be best to have:

• synchronous memory cache
• asynchronous disk cache
• consistency