client_state used in the process_request_one(...) contains all sorts of information irrelevant
to the caller (process_request(...)), e.g. Tracing state. Therefore instead of returning
the whole client_state object (which becomes even a bigger problem if process_one(...) and process_request_one(...)
are executed on different shards) we will return only the pieces of information we really need.
To do that we introduce a new class - processing_result, which is cross-shard-access-ready to begin with.
We are going to return a instance of this new class from the process_request_one(...).
Fixes#2351
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
d06b577b86