Read a value and its version number from the KV store.
Read a value and its version number from the KV store.
The key of the value to get.
A tuple of the value and the version number of the value of the key
Add a value into the KV store only if the current version number is 'version'
Add a value into the KV store only if the current version number is 'version'
True if the operation succeeded else False
Add a value into the KV store
Remove a value from the KV store only if the current version number is "version"
Remove a value form the store.
Simple KV store with consistent read semantics inspired by the spinnaker paper http://www.vldb.org/pvldb/vol4/p243-rao.pdf