Jordan Hrycaj 3e88589eb1
Optional accounts cache module for creating genesis (#1897)
* Split off `ReadOnlyStateDB` from `AccountStateDB` from `state_db.nim`

why:
  Apart from testing, applications use `ReadOnlyStateDB` as an easy
  way to access the accounts ledger. This is well supported by the
  `Aristo` db, but writable mode is only parially supported.

  The writable AccountStateDB` object for modifying accounts is not
  used by production code.

  So, for lecgacy and testing apps, the full support of the previous
  `AccountStateDB` is now enabled by `import db/state_db/read_write`
  and the `import db/state_db` provides read-only mode.

* Encapsulate `AccountStateDB` as `GenesisLedgerRef` or genesis creation

why:
  `AccountStateDB` has poor support for `Aristo` and is not widely used
   in favour of `AccountsLedger` (which will be abstracted as `ledger`.)

   Currently, using other than the `AccountStateDB` ledgers within the
   `GenesisLedgerRef` wrapper is experimental and test only. Eventually,
    the wrapper should disappear so that the `Ledger` object (which
    encapsulates `AccountsCache` and `AccountsLedger`) will prevail.

* For the `Ledger`, provide access to raw accounts `MPT`

why:
  This gives to the `CoreDbMptRef` descriptor from the `CoreDb` (which is
  the legacy version of 	CoreDxMptRef`.) For the new `ledger` API, the
  accounts are based on the `CoreDxMAccRef` descriptor which uses a
  particular sub-system for accounts while legacy applications use the
  `CoreDbPhkRef` equivalent of the `SecureHexaryTrie`.

  The only place where this feature will currently be used is the
 `genesis.nim` source file.

* Fix `Aristo` bugs, missing boundary checks, typos, etc.

* Verify root vertex in `MPT` and account constructors

why:
  Was missing so far, in particular the accounts constructor must
  verify `VertexID(1)

* Fix include file
2023-11-20 11:51:43 +00:00
..
2023-07-31 14:43:38 +01:00

Core database replacement wrapper object

This wrapper replaces the TrieDatabaseRef and its derivatives by the new object CoreDbRef.

Relations to current TrieDatabaseRef implementation

Here are some incomplete translations for objects and constructors.

Object types:

Legacy notation CoreDbRef based replacement
ChainDB (don't use/avoid)
ChainDbRef CoreDbRef
TrieDatabaseRef CoreDbKvtRef
HexaryTrie CoreDbMptRef
SecureHexaryTrie CoreDbPhkRef
DbTransaction CoreDbTxRef
TransactionID CoreDbTxID

Constructors:

Legacy notation CoreDbRef based replacement
trieDB newChainDB("..") newCoreDbRef(LegacyDbPersistent,"..")
newMemoryDB() newCoreDbRef(LegacyDbMemory)
--
initHexaryTrie(db,..) db.mpt(..) (no pruning)
db.mptPrune(..) (w/pruning true/false)
--
initSecureHexaryTrie(db,..) db.phk(..) (no pruning)
db.phkPrune(..) (w/pruning true/false)
--
newCaptureDB(db,memDB) db.capture() (see below)

Usage of the replacement wrapper

Objects pedigree:

    CoreDbRef                   -- base descriptor
     | | | |
     | | | +-- CoreDbMptRef     -- hexary trie instance
     | | | |    :                    :
     | | | +-- CoreDbMptRef     -- hexary trie instance
     | | |
     | | |
     | | +---- CoreDbPhkRef     -- pre-hashed key hexary trie instance
     | | |      :                    :
     | | +---- CoreDbPhkRef     -- pre-hashed key hexary trie instance
     | |
     | |
     | +------ CoreDbKvtRef     -- single static key-value table
     |
     |
     +-------- CoreDbCaptRef    -- tracer support descriptor

Instantiating standard database object descriptors works as follows:

    let
      db = newCoreDbRef(..)           # new base descriptor
      mpt = db.mpt(..)                # hexary trie/Merkle Patricia Tree
      phk = db.phk(..)                # pre-hashed key hexary trie/MPT
      kvt = db.kvt                    # key-value table

Tracer support setup by hiding the current CoreDbRef behind a replacement:

    let
      capture = db.capture()
      db = capture.recorder           # use the recorder in place of db
    ...

    for key,value in capture.recorder.kvt:
     ...                              # process recorded data