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_nibbles, desc_structural],
minilru
from ./aristo_desc/desc_backend
import BackendRef
# Not auto-exporting backend
export
tables, aristo_constants, desc_error, desc_identifiers, desc_nibbles,
desc_structural, minilru, common
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
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 object
## Three tier database object supporting distributed instances.
top*: LayerRef ## Database working layer, mutable
stack*: seq[LayerRef] ## Stashed immutable parent layers
balancer*: LayerRef ## Balance out concurrent backend access
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
accLeaves*: LruCache[Hash32, VertexRef]
## Account path to payload cache - accounts are frequently accessed by
## account path when contracts interact with them - this cache ensures
## that we don't have to re-traverse the storage trie for every such
## interaction
## TODO a better solution would probably be to cache this in a type
## exposed to the high-level API
stoLeaves*: LruCache[Hash32, VertexRef]
## Mixed account/storage path to payload cache - same as above but caches
## the full lookup of storage slots
# Debugging data below, might go away in future
xMap*: Table[HashKey,RootedVertexID] ## For pretty printing/debugging
Leg* = object
## For constructing a `VertexPath`
wp*: VidVtxPair ## Vertex ID and data ref
nibble*: int8 ## Next vertex selector for `Branch` (if any)
Hike* = object
## Trie traversal path
root*: VertexID ## Handy for some fringe cases
legs*: ArrayBuf[NibblesBuf.high + 1, Leg] ## Chain of vertices and IDs
tail*: NibblesBuf ## Portion of non completed path
# ------------------------------------------------------------------------------
# Public helpers
# ------------------------------------------------------------------------------
template mixUp*(accPath, stoPath: Hash32): Hash32 =
# Insecure but fast way of mixing the values of two hashes, for the purpose
# of quick lookups - this is certainly not a good idea for general Hash32
# values but account paths are generated from accounts which would be hard
# to create pre-images for, for the purpose of collisions with a particular
# storage slot
var v {.noinit.}: Hash32
for i in 0..<v.data.len:
# `+` wraps leaving all bits used
v.data[i] = accPath.data[i] + stoPath.data[i]
v
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,RootedVertexID]; w: W): RootedVertexID =
tab.getOrDefault(w, default(RootedVertexID))
func getOrVoid*[W](tab: Table[W,HashSet[RootedVertexID]]; w: W): HashSet[RootedVertexID] =
tab.getOrDefault(w, default(HashSet[RootedVertexID]))
# --------
func isValid*(vtx: VertexRef): bool =
vtx != VertexRef(nil)
func isValid*(nd: NodeRef): bool =
nd != NodeRef(nil)
func isValid*(pid: PathID): bool =
pid != VOID_PATH_ID
func isValid*(layer: LayerRef): bool =
layer != LayerRef(nil)
func isValid*(root: Hash32): bool =
root != EMPTY_ROOT_HASH
func isValid*(key: HashKey): bool =
assert key.len != 32 or key.to(Hash32).isValid
0 < key.len
func isValid*(vid: VertexID): bool =
vid != VertexID(0)
func isValid*(rvid: RootedVertexID): bool =
rvid.vid.isValid and rvid.root.isValid
func isValid*(sqv: HashSet[RootedVertexID]): bool =
sqv.len > 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): Result[void,AristoError] =
## 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
ok()
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,
accLeaves: db.accLeaves,
stoLeaves: db.stoLeaves,
)
if not noFilter:
clone.balancer = db.balancer # Ref is ok here (filters are immutable)
if not noTopLayer:
clone.top = LayerRef.init()
if not db.balancer.isNil:
clone.top.vTop = db.balancer.vTop
else:
let rc = clone.backend.getTuvFn()
if rc.isOk:
clone.top.vTop = rc.value
elif rc.error != GetTuvNotFound:
return err(rc.error)
# Add to peer list of clones
db.dudes.peers.incl clone
ok clone
iterator forked*(db: AristoDbRef): tuple[db: AristoDbRef, isLast: bool] =
## Interate over all non centre descriptors (see comments on `reCentre()`
## for details.)
##
## The second `isLast` yielded loop entry is `true` if the yielded tuple
## is the last entry in the list.
##
if not db.dudes.isNil:
var nLeft = db.dudes.peers.len
for dude in db.dudes.peers.items:
if dude != db.dudes.centre:
nLeft.dec
yield (dude, nLeft == 1)
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(DescNotAllowedOnCentre)
elif db notin db.dudes.peers:
err(DescStaleDescriptor)
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(DescMustBeOnCentre)
db.dudes = DudesRef(nil)
ok()
# ------------------------------------------------------------------------------
# Public helpers
# ------------------------------------------------------------------------------
iterator rstack*(db: AristoDbRef): LayerRef =
# Stack in reverse order
for i in 0..<db.stack.len:
yield db.stack[db.stack.len - i - 1]
proc deltaAtLevel*(db: AristoDbRef, level: int): LayerRef =
if level == 0:
db.top
elif level > 0:
doAssert level <= db.stack.len
db.stack[^level]
elif level == -1:
doAssert db.balancer != nil
db.balancer
elif level == -2:
nil
else:
raiseAssert "Unknown level " & $level
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------