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

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Nim

# nimbus-eth1
# Copyright (c) 2023-2024 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 allow 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/[hashes, sets, tables],
eth/common,
results,
./aristo_constants,
./aristo_desc/[desc_error, desc_identifiers, desc_structural]
from ./aristo_desc/desc_backend
import BackendRef
# Not auto-exporting backend
export
aristo_constants, desc_error, desc_identifiers, desc_structural
type
AristoTxRef* = ref object
## Transaction descriptor
db*: AristoDbRef ## Database descriptor
parent*: AristoTxRef ## Previous transaction
txUid*: uint ## Unique ID among transactions
level*: int ## Stack index for this transaction
MerkleSignRef* = ref object
## Simple Merkle signature calculatior for key-value lists
root*: VertexID
db*: AristoDbRef
count*: uint
error*: AristoError
errKey*: Blob
DudesRef = ref object
## List of peers accessing the same database. This list is layzily
## allocated and might be kept with a single entry, i.e. so that
## `{centre} == peers`.
centre: AristoDbRef ## Link to peer with write permission
peers: HashSet[AristoDbRef] ## List of all peers
AristoDbRef* = ref AristoDbObj
AristoDbObj* = object
## Three tier database object supporting distributed instances.
top*: LayerRef ## Database working layer, mutable
stack*: seq[LayerRef] ## Stashed immutable parent layers
roFilter*: FilterRef ## Apply read filter (locks writing)
backend*: BackendRef ## Backend database (may well be `nil`)
txRef*: AristoTxRef ## Latest active transaction
txUidGen*: uint ## Tx-relative unique number generator
dudes: DudesRef ## Related DB descriptors
# Debugging data below, might go away in future
xMap*: Table[HashKey,HashSet[VertexID]] ## For pretty printing/debugging
AristoDbAction* = proc(db: AristoDbRef) {.gcsafe, raises: [].}
## Generic call back function/closure.
# ------------------------------------------------------------------------------
# Public helpers
# ------------------------------------------------------------------------------
func getOrVoid*[W](tab: Table[W,VertexRef]; w: W): VertexRef =
tab.getOrDefault(w, VertexRef(nil))
func getOrVoid*[W](tab: Table[W,NodeRef]; w: W): NodeRef =
tab.getOrDefault(w, NodeRef(nil))
func getOrVoid*[W](tab: Table[W,HashKey]; w: W): HashKey =
tab.getOrDefault(w, VOID_HASH_KEY)
func getOrVoid*[W](tab: Table[W,VertexID]; w: W): VertexID =
tab.getOrDefault(w, VertexID(0))
func getOrVoid*[W](tab: Table[W,HashSet[VertexID]]; w: W): HashSet[VertexID] =
tab.getOrDefault(w, EmptyVidSet)
# --------
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*(pid: PathID): bool =
pid != VOID_PATH_ID
func isValid*(filter: FilterRef): bool =
filter != FilterRef(nil)
func isValid*(root: Hash256): bool =
root != EMPTY_ROOT_HASH
func isValid*(key: HashKey): bool =
assert key.len != 32 or key.to(Hash256).isValid
0 < key.len
func isValid*(vid: VertexID): bool =
vid != VertexID(0)
func isValid*(sqv: HashSet[VertexID]): bool =
sqv != EmptyVidSet
func isValid*(qid: QueueID): bool =
qid != QueueID(0)
# ------------------------------------------------------------------------------
# Public functions, miscellaneous
# ------------------------------------------------------------------------------
# Hash set helper
func hash*(db: AristoDbRef): Hash =
## Table/KeyedQueue/HashSet mixin
cast[pointer](db).hash
# ------------------------------------------------------------------------------
# Public functions, `dude` related
# ------------------------------------------------------------------------------
func isCentre*(db: AristoDbRef): bool =
## This function returns `true` is the argument `db` is the centre (see
## comments on `reCentre()` for details.)
##
db.dudes.isNil or db.dudes.centre == db
func getCentre*(db: AristoDbRef): AristoDbRef =
## Get the centre descriptor among all other descriptors accessing the same
## backend database (see comments on `reCentre()` for details.)
##
if db.dudes.isNil: db else: db.dudes.centre
proc reCentre*(db: AristoDbRef) =
## Re-focus the `db` argument descriptor so that it becomes the centre.
## Nothing is done if the `db` descriptor is the centre, already.
##
## With several descriptors accessing the same backend database there is a
## single one that has write permission for the backend (regardless whether
## there is a backend, at all.) The descriptor entity with write permission
## is called *the centre*.
##
## After invoking `reCentre()`, the argument database `db` can only be
## destructed by `finish()` which also destructs all other descriptors
## accessing the same backend database. Descriptors where `isCentre()`
## returns `false` must be single destructed with `forget()`.
##
if not db.dudes.isNil:
db.dudes.centre = db
proc fork*(
db: AristoDbRef;
noTopLayer = false;
noFilter = false;
): Result[AristoDbRef,AristoError] =
## This function creates a new empty descriptor accessing the same backend
## (if any) database as the argument `db`. This new descriptor joins the
## list of descriptors accessing the same backend database.
##
## After use, any unused non centre descriptor should be destructed via
## `forget()`. Not doing so will not only hold memory ressources but might
## also cost computing ressources for maintaining and updating backend
## filters when writing to the backend database .
##
## If the argument `noFilter` is set `true` the function will fork directly
## off the backend database and ignore any filter.
##
## If the argument `noTopLayer` is set `true` the function will provide an
## uninitalised and inconsistent (!) descriptor object without top layer.
## This setting avoids some database lookup for cases where the top layer
## is redefined anyway.
##
# Make sure that there is a dudes list
if db.dudes.isNil:
db.dudes = DudesRef(centre: db, peers: @[db].toHashSet)
let clone = AristoDbRef(
dudes: db.dudes,
backend: db.backend)
if not noFilter:
clone.roFilter = db.roFilter # Ref is ok here (filters are immutable)
if not noTopLayer:
clone.top = LayerRef.init()
if not db.roFilter.isNil:
clone.top.final.vGen = db.roFilter.vGen
else:
let rc = clone.backend.getIdgFn()
if rc.isOk:
clone.top.final.vGen = rc.value
elif rc.error != GetIdgNotFound:
return err(rc.error)
# Add to peer list of clones
db.dudes.peers.incl clone
ok clone
iterator forked*(db: AristoDbRef): AristoDbRef =
## Interate over all non centre descriptors (see comments on `reCentre()`
## for details.)
if not db.dudes.isNil:
for dude in db.getCentre.dudes.peers.items:
if dude != db.dudes.centre:
yield dude
func nForked*(db: AristoDbRef): int =
## Returns the number of non centre descriptors (see comments on `reCentre()`
## for details.) This function is a fast version of `db.forked.toSeq.len`.
if not db.dudes.isNil:
return db.dudes.peers.len - 1
proc forget*(db: AristoDbRef): Result[void,AristoError] =
## Destruct the non centre argument `db` descriptor (see comments on
## `reCentre()` for details.)
##
## A non centre descriptor should always be destructed after use (see also
## comments on `fork()`.)
##
if db.isCentre:
err(NotAllowedOnCentre)
elif db notin db.dudes.peers:
err(StaleDescriptor)
else:
db.dudes.peers.excl db # Unlink argument `db` from peers list
ok()
proc forgetOthers*(db: AristoDbRef): Result[void,AristoError] =
## For the centre argument `db` descriptor (see comments on `reCentre()`
## for details), destruct all other descriptors accessing the same backend.
##
if not db.dudes.isNil:
if db.dudes.centre != db:
return err(MustBeOnCentre)
db.dudes = DudesRef(nil)
ok()
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------