replace optional params in WritableKeystore with metadata object

[murali-shris]

Is your feature request related to a problem? Please describe.

• Introducing new fields in metadata results in code changes in multiple places and also a breaking change in persistence spec
  Code changes required
• Introduce optional params in WritableKeystore (put/create methods) in peristence_spec. This results in compilation error in persistence secondary forcing to override these new params.
  This is a breaking change in persistence spec
• Changes to AtKey → Metadata in at_commons, AtMetaData in persistence secondary server
• Impl changes to HiveKeyStore and NotificationKeyStore
• Add new field in implementation in AbstractUpdateVerbHandler , UpdateVerbHandler and ResourceManager

Describe the solution you'd like

• Modify WritableKeystore signature from put(K key, V value, {int? time_to_live, int? time_to_born, int? time_to_refresh....)
  to put (K key, V value, Metadata metadata)
• Similar change for create method
• Explore whether some of the common logic in ResourceManager and AbstractVerbHandler can be moved to a common place.

Describe alternatives you've considered

No response

Additional context

No response

[sitaram-kalluri]

The AtData class, which encapsulates the value of a key, currently includes both the value itself and its associated metadata. We previously considered maintaining metadata in a separate hive store. Can we consider with removing metadata from AtData and instead storing it in a separate data store?

[murali-shris]

The AtData class, which encapsulates the value of a key, currently includes both the value itself and its associated metadata. We previously considered maintaining metadata in a separate hive store. Can we consider with removing metadata from AtData and instead storing it in a separate data store?

@gkc please give your inputs on this change

[gkc]

Not yet. We've not yet decided which next pieces of server optimization to tackle, nor in what order.

[murali-shris]

Code changes done in persistence spec and persistence impl
https://github.com/atsign-foundation/at_server/tree/persistence_spec_refactoring
https://github.com/atsign-foundation/at_server/tree/persistence_impl_refactoring
Pending. Raise PR after testing uptake in at_client and at_server