215 lines
7.5 KiB
Nim
215 lines
7.5 KiB
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.
|
|
|
|
## Kvt DB -- key-value table
|
|
## =========================
|
|
##
|
|
{.push raises: [].}
|
|
|
|
import
|
|
std/[hashes, sets, tables],
|
|
eth/common,
|
|
results,
|
|
./kvt_constants,
|
|
./kvt_desc/[desc_error, desc_structural]
|
|
|
|
from ./kvt_desc/desc_backend import BackendRef
|
|
|
|
# Not auto-exporting backend
|
|
export kvt_constants, desc_error, desc_structural
|
|
|
|
type
|
|
KvtTxRef* = ref object ## Transaction descriptor
|
|
db*: KvtDbRef ## Database descriptor
|
|
parent*: KvtTxRef ## 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: KvtDbRef ## Link to peer with write permission
|
|
peers: HashSet[KvtDbRef] ## List of all peers
|
|
|
|
KvtDbRef* = ref object of RootRef
|
|
## 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*: KvtTxRef ## Latest active transaction
|
|
txUidGen*: uint ## Tx-relative unique number generator
|
|
dudes: DudesRef ## Related DB descriptors
|
|
|
|
# Debugging data below, might go away in future
|
|
xIdGen*: uint64
|
|
xMap*: Table[Blob, uint64] ## For pretty printing
|
|
pAmx*: Table[uint64, Blob] ## For pretty printing
|
|
|
|
KvtDbAction* = proc(db: KvtDbRef) {.gcsafe, raises: [].}
|
|
## Generic call back function/closure.
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Private helpers
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc canMod(db: KvtDbRef): Result[void, KvtError] =
|
|
## Ask for permission before doing nasty stuff
|
|
if db.backend.isNil:
|
|
ok()
|
|
else:
|
|
db.backend.canModFn()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public helpers
|
|
# ------------------------------------------------------------------------------
|
|
|
|
func getOrVoid*(tab: Table[Blob, Blob], w: Blob): Blob =
|
|
tab.getOrDefault(w, EmptyBlob)
|
|
|
|
func isValid*(key: Blob): bool =
|
|
key != EmptyBlob
|
|
|
|
func isValid*(layer: LayerRef): bool =
|
|
layer != LayerRef(nil)
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions, miscellaneous
|
|
# ------------------------------------------------------------------------------
|
|
|
|
# Hash set helper
|
|
func hash*(db: KvtDbRef): Hash =
|
|
## Table/KeyedQueue/HashSet mixin
|
|
cast[pointer](db).hash
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions, `dude` related
|
|
# ------------------------------------------------------------------------------
|
|
|
|
func isCentre*(db: KvtDbRef): 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: KvtDbRef): KvtDbRef =
|
|
## 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: KvtDbRef): Result[void, KvtError] =
|
|
## 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 and db.dudes.centre != db:
|
|
?db.canMod()
|
|
db.dudes.centre = db
|
|
ok()
|
|
|
|
proc fork*(
|
|
db: KvtDbRef, noTopLayer = false, noFilter = false
|
|
): Result[KvtDbRef, KvtError] =
|
|
## 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.
|
|
##
|
|
# Make sure that there is a dudes list
|
|
if db.dudes.isNil:
|
|
db.dudes = DudesRef(centre: db, peers: @[db].toHashSet)
|
|
|
|
let clone = KvtDbRef(backend: db.backend, dudes: db.dudes)
|
|
|
|
if not noFilter:
|
|
clone.balancer = db.balancer # Ref is ok here (filters are immutable)
|
|
|
|
if not noTopLayer:
|
|
clone.top = LayerRef.init()
|
|
|
|
# Add to peer list of clones
|
|
db.dudes.peers.incl clone
|
|
|
|
ok clone
|
|
|
|
iterator forked*(db: KvtDbRef): tuple[db: KvtDbRef, 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: KvtDbRef): 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: KvtDbRef): Result[void, KvtError] =
|
|
## 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.canMod()
|
|
db.dudes.peers.excl db # Unlink argument `db` from peers list
|
|
ok()
|
|
|
|
proc forgetOthers*(db: KvtDbRef): Result[void, KvtError] =
|
|
## For the centre argument `db` descriptor (see comments on `reCentre()`
|
|
## for details), release all other descriptors accessing the same backend.
|
|
##
|
|
if not db.dudes.isNil:
|
|
if db.dudes.centre != db:
|
|
return err(MustBeOnCentre)
|
|
?db.canMod()
|
|
db.dudes = DudesRef(nil)
|
|
ok()
|
|
|
|
iterator rstack*(db: KvtDbRef): LayerRef =
|
|
# Stack in reverse order
|
|
for i in 0 ..< db.stack.len:
|
|
yield db.stack[db.stack.len - i - 1]
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# End
|
|
# ------------------------------------------------------------------------------
|