nimbus-eth1/nimbus/db/aristo/aristo_desc.nim

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# nimbus-eth1
# Copyright (c) 2021 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
# http://www.apache.org/licenses/LICENSE-2.0)
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
# http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed
# except according to those terms.
## Aristo DB -- a Patricia Trie with labeled edges
## ===============================================
##
## These data structures allows to overlay the *Patricia Trie* with *Merkel
## Trie* hashes. See the `README.md` in the `aristo` folder for documentation.
##
## Some semantic explanations;
##
## * HashKey, NodeRef etc. refer to the standard/legacy `Merkle Patricia Tree`
## * VertexID, VertexRef, etc. refer to the `Aristo Trie`
##
{.push raises: [].}
import
std/[sets, tables],
eth/common,
./aristo_constants,
./aristo_desc/[
aristo_error, aristo_types_backend,
aristo_types_identifiers, aristo_types_structural]
export
# Not auto-exporting backend
aristo_constants, aristo_error, aristo_types_identifiers,
aristo_types_structural
type
AristoChangeLogRef* = ref object
## Change log: database state before backend saving.
root*: HashKey ## Previous hash key for `VertexID(1)`
leafs*: Table[LeafTie,PayloadRef] ## Changed leafs after merge into backend
AristoLayerRef* = ref object
## Hexary trie database layer structures. Any layer holds the full
## change relative to the backend.
sTab*: Table[VertexID,VertexRef] ## Structural vertex table
lTab*: Table[LeafTie,VertexID] ## Direct access, path to leaf vertex
kMap*: Table[VertexID,HashLabel] ## Merkle hash key mapping
pAmk*: Table[HashLabel,VertexID] ## Reverse `kMap` entries, hash key lookup
pPrf*: HashSet[VertexID] ## Locked vertices (proof nodes)
vGen*: seq[VertexID] ## Unique vertex ID generator
AristoDbRef* = ref AristoDbObj
AristoDbObj* = object
## Set of database layers, supporting transaction frames
top*: AristoLayerRef ## Database working layer, mutable
stack*: seq[AristoLayerRef] ## Stashed immutable parent layers
backend*: AristoBackendRef ## Backend database (may well be `nil`)
history*: seq[AristoChangeLogRef] ## Backend saving history
# Debugging data below, might go away in future
xMap*: Table[HashLabel,VertexID] ## For pretty printing, extends `pAmk`
# ------------------------------------------------------------------------------
# Public helpers
# ------------------------------------------------------------------------------
func getOrVoid*[W](tab: Table[W,VertexRef]; w: W): VertexRef =
tab.getOrDefault(w, VertexRef(nil))
func getOrVoid*[W](tab: Table[W,HashLabel]; w: W): HashLabel =
tab.getOrDefault(w, VOID_HASH_LABEL)
func getOrVoid*[W](tab: Table[W,VertexID]; w: W): VertexID =
tab.getOrDefault(w, VertexID(0))
# --------
func isValid*(vtx: VertexRef): bool =
vtx != VertexRef(nil)
func isValid*(nd: NodeRef): bool =
nd != NodeRef(nil)
func isValid*(pld: PayloadRef): bool =
pld != PayloadRef(nil)
func isValid*(key: HashKey): bool =
key != VOID_HASH_KEY
func isValid*(lbl: HashLabel): bool =
lbl != VOID_HASH_LABEL
func isValid*(vid: VertexID): bool =
vid != VertexID(0)
# ------------------------------------------------------------------------------
# Public functions, miscellaneous
# ------------------------------------------------------------------------------
# Note that the below `init()` function cannot go into
# `aristo_types_identifiers` as this would result in a circular import.
func init*(key: var HashKey; data: openArray[byte]): bool =
## Import argument `data` into `key` which must have length either `32`, or
## `0`. The latter case is equivalent to an all zero byte array of size `32`.
if data.len == 32:
(addr key.ByteArray32[0]).copyMem(unsafeAddr data[0], data.len)
return true
if data.len == 0:
key = VOID_HASH_KEY
return true
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------