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

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# nimbus-eth1
Core db update storage root management for sub tries (#1964) * Aristo: Re-phrase `LayerDelta` and `LayerFinal` as object references why: Avoids copying in some cases * Fix copyright header * Aristo: Verify `leafTie.root` function argument for `merge()` proc why: Zero root will lead to inconsistent DB entry * Aristo: Update failure condition for hash labels compiler `hashify()` why: Node need not be rejected as long as links are on the schedule. In that case, `redo[]` is to become `wff.base[]` at a later stage. This amends an earlier fix, part of #1952 by also testing against the target nodes of the `wff.base[]` sets. * Aristo: Add storage root glue record to `hashify()` schedule why: An account leaf node might refer to a non-resolvable storage root ID. Storage root node chains will end up at the storage root. So the link `storage-root->account-leaf` needs an extra item in the schedule. * Aristo: fix error code returned by `fetchPayload()` details: Final error code is implied by the error code form the `hikeUp()` function. * CoreDb: Discard `createOk` argument in API `getRoot()` function why: Not needed for the legacy DB. For the `Arsto` DB, a lazy approach is implemented where a stprage root node is created on-the-fly. * CoreDb: Prevent `$$` logging in some cases why: Logging the function `$$` is not useful when it is used for internal use, i.e. retrieving an an error text for logging. * CoreDb: Add `tryHashFn()` to API for pretty printing why: Pretty printing must not change the hashification status for the `Aristo` DB. So there is an independent API wrapper for getting the node hash which never updated the hashes. * CoreDb: Discard `update` argument in API `hash()` function why: When calling the API function `hash()`, the latest state is always wanted. For a version that uses the current state as-is without checking, the function `tryHash()` was added to the backend. * CoreDb: Update opaque vertex ID objects for the `Aristo` backend why: For `Aristo`, vID objects encapsulate a numeric `VertexID` referencing a vertex (rather than a node hash as used on the legacy backend.) For storage sub-tries, there might be no initial vertex known when the descriptor is created. So opaque vertex ID objects are supported without a valid `VertexID` which will be initalised on-the-fly when the first item is merged. * CoreDb: Add pretty printer for opaque vertex ID objects * Cosmetics, printing profiling data * CoreDb: Fix segfault in `Aristo` backend when creating MPT descriptor why: Missing initialisation error * CoreDb: Allow MPT to inherit shared context on `Aristo` backend why: Creates descriptors with different storage roots for the same shared `Aristo` DB descriptor. * Cosmetics, update diagnostic message items for `Aristo` backend * Fix Copyright year
2024-01-11 19:11:38 +00:00
# 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
Aristo db update for short nodes key edge cases (#1887) * Aristo: Provide key-value list signature calculator detail: Simple wrappers around `Aristo` core functionality * Update new API for `CoreDb` details: + Renamed new API functions `contains()` => `hasKey()` or `hasPath()` which disables the `in` operator on non-boolean `contains()` functions + The functions `get()` and `fetch()` always return a not-found error if there is no item, available. The new functions `getOrEmpty()` and `mergeOrEmpty()` return an an empty `Blob` if there is no such key found. * Rewrite `core_apps.nim` using new API from `CoreDb` * Use `Aristo` functionality for calculating Merkle signatures details: For debugging, the `VerifyAristoForMerkleRootCalc` can be set so that `Aristo` results will be verified against the legacy versions. * Provide general interface for Merkle signing key-value tables details: Export `Aristo` wrappers * Activate `CoreDb` tests why: Now, API seems to be stable enough for general tests. * Update `toHex()` usage why: Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join` * Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify` why: + Different modules for different purposes + `aristo_serialise`: RLP encoding/decoding + `aristo_blobify`: Aristo database encoding/decoding * Compacted representation of small nodes' links instead of Keccak hashes why: Ethereum MPTs use Keccak hashes as node links if the size of an RLP encoded node is at least 32 bytes. Otherwise, the RLP encoded node value is used as a pseudo node link (rather than a hash.) Such a node is nor stored on key-value database. Rather the RLP encoded node value is stored instead of a lode link in a parent node instead. Only for the root hash, the top level node is always referred to by the hash. This feature needed an abstraction of the `HashKey` object which is now either a hash or a blob of length at most 31 bytes. This leaves two ways of representing an empty/void `HashKey` type, either as an empty blob of zero length, or the hash of an empty blob. * Update `CoreDb` interface (mainly reducing logger noise) * Fix copyright years (to make `Lint` happy)
2023-11-08 12:18:32 +00:00
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
Core db update providing additional results code interface (#1776) * Split `core_db/base.nim` into several sources * Rename `core_db/legacy.nim` => `core_db/legacy_db.nim` * Update `CoreDb` API, dual methods returning `Result[]` or plain value detail: Plain value methods implemet the legacy API, they defect on error results * Redesign `CoreDB` direct backend access why: Made the `backend` directive integral part of the API * Discontinue providing unused or otherwise available functions details: + setTransactionID() removed, not used and not easily replicable in Aristo + maybeGet() removed, available via direct backend access + newPhk() removed, never used & was experimental anyway * Update/reorg backend API why: + Added error print function `$$()` + General descriptor completion (and optional validation) via `bless()` * Update `Aristo`/`Kvt` exception handling why: Avoid `CatchableError` exceptions, rather pass them as error code where appropriate. * More `CoreDB` compliant `Aristo` and `Kvt` methods details: + Providing functions like `contains()`, `getVtxRc()` (returns `Result[]`). + Additional error code: `NotImplemented` * Rewrite/reorg of Aristo DB constructor why: Previously used global object `DefaultQidLayoutRef` as default initialiser. This object was created at compile time which lead to non-gc safe functions. * Update nimbus/db/core_db/legacy_db.nim Co-authored-by: Kim De Mey <kim.demey@gmail.com> * Update nimbus/db/aristo/aristo_transcode.nim Co-authored-by: Kim De Mey <kim.demey@gmail.com> * Update nimbus/db/core_db/legacy_db.nim Co-authored-by: Kim De Mey <kim.demey@gmail.com> --------- Co-authored-by: Kim De Mey <kim.demey@gmail.com>
2023-09-26 09:21:13 +00:00
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))
Aristo db update for short nodes key edge cases (#1887) * Aristo: Provide key-value list signature calculator detail: Simple wrappers around `Aristo` core functionality * Update new API for `CoreDb` details: + Renamed new API functions `contains()` => `hasKey()` or `hasPath()` which disables the `in` operator on non-boolean `contains()` functions + The functions `get()` and `fetch()` always return a not-found error if there is no item, available. The new functions `getOrEmpty()` and `mergeOrEmpty()` return an an empty `Blob` if there is no such key found. * Rewrite `core_apps.nim` using new API from `CoreDb` * Use `Aristo` functionality for calculating Merkle signatures details: For debugging, the `VerifyAristoForMerkleRootCalc` can be set so that `Aristo` results will be verified against the legacy versions. * Provide general interface for Merkle signing key-value tables details: Export `Aristo` wrappers * Activate `CoreDb` tests why: Now, API seems to be stable enough for general tests. * Update `toHex()` usage why: Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join` * Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify` why: + Different modules for different purposes + `aristo_serialise`: RLP encoding/decoding + `aristo_blobify`: Aristo database encoding/decoding * Compacted representation of small nodes' links instead of Keccak hashes why: Ethereum MPTs use Keccak hashes as node links if the size of an RLP encoded node is at least 32 bytes. Otherwise, the RLP encoded node value is used as a pseudo node link (rather than a hash.) Such a node is nor stored on key-value database. Rather the RLP encoded node value is stored instead of a lode link in a parent node instead. Only for the root hash, the top level node is always referred to by the hash. This feature needed an abstraction of the `HashKey` object which is now either a hash or a blob of length at most 31 bytes. This leaves two ways of representing an empty/void `HashKey` type, either as an empty blob of zero length, or the hash of an empty blob. * Update `CoreDb` interface (mainly reducing logger noise) * Fix copyright years (to make `Lint` happy)
2023-11-08 12:18:32 +00:00
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))
Aristo db update for short nodes key edge cases (#1887) * Aristo: Provide key-value list signature calculator detail: Simple wrappers around `Aristo` core functionality * Update new API for `CoreDb` details: + Renamed new API functions `contains()` => `hasKey()` or `hasPath()` which disables the `in` operator on non-boolean `contains()` functions + The functions `get()` and `fetch()` always return a not-found error if there is no item, available. The new functions `getOrEmpty()` and `mergeOrEmpty()` return an an empty `Blob` if there is no such key found. * Rewrite `core_apps.nim` using new API from `CoreDb` * Use `Aristo` functionality for calculating Merkle signatures details: For debugging, the `VerifyAristoForMerkleRootCalc` can be set so that `Aristo` results will be verified against the legacy versions. * Provide general interface for Merkle signing key-value tables details: Export `Aristo` wrappers * Activate `CoreDb` tests why: Now, API seems to be stable enough for general tests. * Update `toHex()` usage why: Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join` * Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify` why: + Different modules for different purposes + `aristo_serialise`: RLP encoding/decoding + `aristo_blobify`: Aristo database encoding/decoding * Compacted representation of small nodes' links instead of Keccak hashes why: Ethereum MPTs use Keccak hashes as node links if the size of an RLP encoded node is at least 32 bytes. Otherwise, the RLP encoded node value is used as a pseudo node link (rather than a hash.) Such a node is nor stored on key-value database. Rather the RLP encoded node value is stored instead of a lode link in a parent node instead. Only for the root hash, the top level node is always referred to by the hash. This feature needed an abstraction of the `HashKey` object which is now either a hash or a blob of length at most 31 bytes. This leaves two ways of representing an empty/void `HashKey` type, either as an empty blob of zero length, or the hash of an empty blob. * Update `CoreDb` interface (mainly reducing logger noise) * Fix copyright years (to make `Lint` happy)
2023-11-08 12:18:32 +00:00
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)
Aristo db update for short nodes key edge cases (#1887) * Aristo: Provide key-value list signature calculator detail: Simple wrappers around `Aristo` core functionality * Update new API for `CoreDb` details: + Renamed new API functions `contains()` => `hasKey()` or `hasPath()` which disables the `in` operator on non-boolean `contains()` functions + The functions `get()` and `fetch()` always return a not-found error if there is no item, available. The new functions `getOrEmpty()` and `mergeOrEmpty()` return an an empty `Blob` if there is no such key found. * Rewrite `core_apps.nim` using new API from `CoreDb` * Use `Aristo` functionality for calculating Merkle signatures details: For debugging, the `VerifyAristoForMerkleRootCalc` can be set so that `Aristo` results will be verified against the legacy versions. * Provide general interface for Merkle signing key-value tables details: Export `Aristo` wrappers * Activate `CoreDb` tests why: Now, API seems to be stable enough for general tests. * Update `toHex()` usage why: Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join` * Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify` why: + Different modules for different purposes + `aristo_serialise`: RLP encoding/decoding + `aristo_blobify`: Aristo database encoding/decoding * Compacted representation of small nodes' links instead of Keccak hashes why: Ethereum MPTs use Keccak hashes as node links if the size of an RLP encoded node is at least 32 bytes. Otherwise, the RLP encoded node value is used as a pseudo node link (rather than a hash.) Such a node is nor stored on key-value database. Rather the RLP encoded node value is stored instead of a lode link in a parent node instead. Only for the root hash, the top level node is always referred to by the hash. This feature needed an abstraction of the `HashKey` object which is now either a hash or a blob of length at most 31 bytes. This leaves two ways of representing an empty/void `HashKey` type, either as an empty blob of zero length, or the hash of an empty blob. * Update `CoreDb` interface (mainly reducing logger noise) * Fix copyright years (to make `Lint` happy)
2023-11-08 12:18:32 +00:00
func isValid*(root: Hash256): bool =
root != EMPTY_ROOT_HASH
Aristo db update for short nodes key edge cases (#1887) * Aristo: Provide key-value list signature calculator detail: Simple wrappers around `Aristo` core functionality * Update new API for `CoreDb` details: + Renamed new API functions `contains()` => `hasKey()` or `hasPath()` which disables the `in` operator on non-boolean `contains()` functions + The functions `get()` and `fetch()` always return a not-found error if there is no item, available. The new functions `getOrEmpty()` and `mergeOrEmpty()` return an an empty `Blob` if there is no such key found. * Rewrite `core_apps.nim` using new API from `CoreDb` * Use `Aristo` functionality for calculating Merkle signatures details: For debugging, the `VerifyAristoForMerkleRootCalc` can be set so that `Aristo` results will be verified against the legacy versions. * Provide general interface for Merkle signing key-value tables details: Export `Aristo` wrappers * Activate `CoreDb` tests why: Now, API seems to be stable enough for general tests. * Update `toHex()` usage why: Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join` * Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify` why: + Different modules for different purposes + `aristo_serialise`: RLP encoding/decoding + `aristo_blobify`: Aristo database encoding/decoding * Compacted representation of small nodes' links instead of Keccak hashes why: Ethereum MPTs use Keccak hashes as node links if the size of an RLP encoded node is at least 32 bytes. Otherwise, the RLP encoded node value is used as a pseudo node link (rather than a hash.) Such a node is nor stored on key-value database. Rather the RLP encoded node value is stored instead of a lode link in a parent node instead. Only for the root hash, the top level node is always referred to by the hash. This feature needed an abstraction of the `HashKey` object which is now either a hash or a blob of length at most 31 bytes. This leaves two ways of representing an empty/void `HashKey` type, either as an empty blob of zero length, or the hash of an empty blob. * Update `CoreDb` interface (mainly reducing logger noise) * Fix copyright years (to make `Lint` happy)
2023-11-08 12:18:32 +00:00
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)
Aristo db update for short nodes key edge cases (#1887) * Aristo: Provide key-value list signature calculator detail: Simple wrappers around `Aristo` core functionality * Update new API for `CoreDb` details: + Renamed new API functions `contains()` => `hasKey()` or `hasPath()` which disables the `in` operator on non-boolean `contains()` functions + The functions `get()` and `fetch()` always return a not-found error if there is no item, available. The new functions `getOrEmpty()` and `mergeOrEmpty()` return an an empty `Blob` if there is no such key found. * Rewrite `core_apps.nim` using new API from `CoreDb` * Use `Aristo` functionality for calculating Merkle signatures details: For debugging, the `VerifyAristoForMerkleRootCalc` can be set so that `Aristo` results will be verified against the legacy versions. * Provide general interface for Merkle signing key-value tables details: Export `Aristo` wrappers * Activate `CoreDb` tests why: Now, API seems to be stable enough for general tests. * Update `toHex()` usage why: Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join` * Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify` why: + Different modules for different purposes + `aristo_serialise`: RLP encoding/decoding + `aristo_blobify`: Aristo database encoding/decoding * Compacted representation of small nodes' links instead of Keccak hashes why: Ethereum MPTs use Keccak hashes as node links if the size of an RLP encoded node is at least 32 bytes. Otherwise, the RLP encoded node value is used as a pseudo node link (rather than a hash.) Such a node is nor stored on key-value database. Rather the RLP encoded node value is stored instead of a lode link in a parent node instead. Only for the root hash, the top level node is always referred to by the hash. This feature needed an abstraction of the `HashKey` object which is now either a hash or a blob of length at most 31 bytes. This leaves two ways of representing an empty/void `HashKey` type, either as an empty blob of zero length, or the hash of an empty blob. * Update `CoreDb` interface (mainly reducing logger noise) * Fix copyright years (to make `Lint` happy)
2023-11-08 12:18:32 +00:00
func isValid*(sqv: HashSet[VertexID]): bool =
sqv != EmptyVidSet
func isValid*(qid: QueueID): bool =
qid != QueueID(0)
func isValid*(fid: FilterID): bool =
fid != FilterID(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
Aristo db api extensions for use as core db backend (#1754) * Update docu * Update Aristo/Kvt constructor prototype why: Previous version used an `enum` value to indicate what backend is to be used. This was replaced by using the backend object type. * Rewrite `hikeUp()` return code into `Result[Hike,(Hike,AristoError)]` why: Better code maintenance. Previously, the `Hike` object was returned. It had an internal error field so partial success was also available on a failure. This error field has been removed. * Use `openArray[byte]` rather than `Blob` in functions prototypes * Provide synchronised multi instance transactions why: The `CoreDB` object was geared towards the legacy DB which used a single transaction for the key-value backend DB. Different state roots are provided by the backend database, so all instances work directly on the same backend. Aristo db instances have different in-memory mappings (aka different state roots) and the transactions are on top of there mappings. So each instance might run different transactions. Multi instance transactions are a compromise to converge towards the legacy behaviour. The synchronised transactions span over all instances available at the time when base transaction was opened. Instances created later are unaffected. * Provide key-value pair database iterator why: Needed in `CoreDB` for `replicate()` emulation also: Some update of internal code * Extend API (i.e. prototype variants) why: Needed for `CoreDB` geared towards the legacy backend which has a more basic API than Aristo.
2023-09-15 15:23:53 +00:00
proc fork*(
db: AristoDbRef;
noTopLayer = 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 `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 noTopLayer:
clone.top = LayerRef.init()
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`.
Aristo db api extensions for use as core db backend (#1754) * Update docu * Update Aristo/Kvt constructor prototype why: Previous version used an `enum` value to indicate what backend is to be used. This was replaced by using the backend object type. * Rewrite `hikeUp()` return code into `Result[Hike,(Hike,AristoError)]` why: Better code maintenance. Previously, the `Hike` object was returned. It had an internal error field so partial success was also available on a failure. This error field has been removed. * Use `openArray[byte]` rather than `Blob` in functions prototypes * Provide synchronised multi instance transactions why: The `CoreDB` object was geared towards the legacy DB which used a single transaction for the key-value backend DB. Different state roots are provided by the backend database, so all instances work directly on the same backend. Aristo db instances have different in-memory mappings (aka different state roots) and the transactions are on top of there mappings. So each instance might run different transactions. Multi instance transactions are a compromise to converge towards the legacy behaviour. The synchronised transactions span over all instances available at the time when base transaction was opened. Instances created later are unaffected. * Provide key-value pair database iterator why: Needed in `CoreDB` for `replicate()` emulation also: Some update of internal code * Extend API (i.e. prototype variants) why: Needed for `CoreDB` geared towards the legacy backend which has a more basic API than Aristo.
2023-09-15 15:23:53 +00:00
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
# ------------------------------------------------------------------------------