* Remove concept of empty/blind filters
why:
Not needed. A non-existent filter is is coded as a nil reference.
* Slightly generalised backend iterators
why:
* VertexID as key for the ID generator state makes no sense
* there will be more tables addressed by non-VertexID keys
* Store serialised/blobified vertices on memory backend
why:
This is more in line with the RocksDB backend so more appropriate
for testing when comparing behaviour. For a speedy memory database,
a backend-less variant should be used.
* Drop the `Aristo` prefix from names `AristoLayerRef`, etc.
* Suppress compiler warning
why:
duplicate imports
* Add filter serialisation transcoder
why:
Will be used as storage format
* Renamed type `NoneBackendRef` => `VoidBackendRef`
* Clarify names: `BE=filter+backend` and `UBE=backend (unfiltered)`
why:
Most functions used full names as `getVtxUnfilteredBackend()` or
`getKeyBackend()`. After defining abbreviations (and its meaning) it
seems easier to use `getVtxUBE()` and `getKeyBE()`.
* Integrate `hashify()` process into transaction logic
why:
Is now transparent unless explicitly controlled.
details:
Cache changes imply setting a `dirty` flag which in turn triggers
`hashify()` processing in transaction and `pack()` directives.
* Removed `aristo_tx.exec()` directive
why:
Inconsistent implementation, functionality will be provided with a
different paradigm.
* Provide deep copy for each transaction layer
why:
Localising changes. Selective deep copy was just overlooked.
* Generalise vertex ID generator state reorg function `vidReorg()`
why:
makes it somewhat easier to handle when saving layers.
* Provide dummy back end descriptor `NoneBackendRef`
* Optional read-only filter between backend and transaction cache
why:
Some staging area for accumulating changes to the backend DB. This
will eventually be an access layer for emulating a backend with
multiple/historic state roots.
* Re-factor `persistent()` with filter between backend/tx-cache => `stow()`
why:
The filter provides an abstraction from the physically stored data on
disk. So, there can be several MPT instances using the same disk data
with different state roots. Of course, all the MPT instances should
not differ too much for practical reasons :).
TODO:
Filter administration tools need to be provided.
* Better error handling
why:
Bail out on some error as early as possible before any changes.
* Implement `fetch()` as opposite of `merge()`
rationale:
In the `Aristo` realm, the action named `fetch()` and `merge()` indicate
leaf value related actions on the MPT, while actions `get()` and `put()`
handle vertex or hash key related operations that constitute the MPT.
* Re-factor `merge()` prototypes
why:
The most used variant of `merge()` should have the simplest prototype.
* Persistent DB constructor needs to import `aristo/aristo_init/persistent`
why:
Most applications use memory DB anyway. This avoids linking `-lrocksdb`
or any other back end libraries by default.
* Re-factor transaction module
why:
Got the paradigm wrong. The transaction descriptor did replace the
database one but should be handled separately.
Jordan Hrycaj