272 lines
9.3 KiB
Nim
272 lines
9.3 KiB
Nim
# nimbus-eth1
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# Copyright (c) 2023-2024 Status Research & Development GmbH
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# Licensed under either of
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
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# http://www.apache.org/licenses/LICENSE-2.0)
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# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
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# http://opensource.org/licenses/MIT)
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# at your option. This file may not be copied, modified, or distributed
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# except according to those terms.
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## Aristo DB -- a Patricia Trie with labeled edges
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## ===============================================
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##
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## These data structures allow to overlay the *Patricia Trie* with *Merkel
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## Trie* hashes. See the `README.md` in the `aristo` folder for documentation.
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##
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## Some semantic explanations;
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##
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## * HashKey, NodeRef etc. refer to the standard/legacy `Merkle Patricia Tree`
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## * VertexID, VertexRef, etc. refer to the `Aristo Trie`
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##
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{.push raises: [].}
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import
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std/[hashes, sets, tables],
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eth/common,
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results,
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./aristo_constants,
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./aristo_desc/[desc_error, desc_identifiers, desc_structural]
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from ./aristo_desc/desc_backend
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import BackendRef
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# Not auto-exporting backend
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export
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aristo_constants, desc_error, desc_identifiers, desc_structural
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type
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AristoTxRef* = ref object
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## Transaction descriptor
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db*: AristoDbRef ## Database descriptor
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parent*: AristoTxRef ## Previous transaction
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txUid*: uint ## Unique ID among transactions
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level*: int ## Stack index for this transaction
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MerkleSignRef* = ref object
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## Simple Merkle signature calculatior for key-value lists
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root*: VertexID
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db*: AristoDbRef
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count*: uint
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error*: AristoError
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errKey*: Blob
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DudesRef = ref object
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## List of peers accessing the same database. This list is layzily
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## allocated and might be kept with a single entry, i.e. so that
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## `{centre} == peers`.
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centre: AristoDbRef ## Link to peer with write permission
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peers: HashSet[AristoDbRef] ## List of all peers
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AristoDbRef* = ref object
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## Three tier database object supporting distributed instances.
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top*: LayerRef ## Database working layer, mutable
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stack*: seq[LayerRef] ## Stashed immutable parent layers
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balancer*: LayerDeltaRef ## Baland out concurrent backend access
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backend*: BackendRef ## Backend database (may well be `nil`)
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txRef*: AristoTxRef ## Latest active transaction
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txUidGen*: uint ## Tx-relative unique number generator
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dudes: DudesRef ## Related DB descriptors
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# Debugging data below, might go away in future
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xMap*: Table[HashKey,HashSet[VertexID]] ## For pretty printing/debugging
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AristoDbAction* = proc(db: AristoDbRef) {.gcsafe, raises: [].}
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## Generic call back function/closure.
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# ------------------------------------------------------------------------------
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# Public helpers
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# ------------------------------------------------------------------------------
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func getOrVoid*[W](tab: Table[W,VertexRef]; w: W): VertexRef =
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tab.getOrDefault(w, VertexRef(nil))
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func getOrVoid*[W](tab: Table[W,NodeRef]; w: W): NodeRef =
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tab.getOrDefault(w, NodeRef(nil))
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func getOrVoid*[W](tab: Table[W,HashKey]; w: W): HashKey =
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tab.getOrDefault(w, VOID_HASH_KEY)
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func getOrVoid*[W](tab: Table[W,VertexID]; w: W): VertexID =
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tab.getOrDefault(w, VertexID(0))
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func getOrVoid*[W](tab: Table[W,HashSet[VertexID]]; w: W): HashSet[VertexID] =
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tab.getOrDefault(w, EmptyVidSet)
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# --------
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func isValid*(vtx: VertexRef): bool =
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vtx != VertexRef(nil)
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func isValid*(nd: NodeRef): bool =
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nd != NodeRef(nil)
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func isValid*(pld: PayloadRef): bool =
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pld != PayloadRef(nil)
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func isValid*(pid: PathID): bool =
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pid != VOID_PATH_ID
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func isValid*(filter: LayerDeltaRef): bool =
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filter != LayerDeltaRef(nil)
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func isValid*(root: Hash256): bool =
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root != EMPTY_ROOT_HASH
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func isValid*(key: HashKey): bool =
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assert key.len != 32 or key.to(Hash256).isValid
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0 < key.len
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func isValid*(vid: VertexID): bool =
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vid != VertexID(0)
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func isValid*(sqv: HashSet[VertexID]): bool =
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sqv != EmptyVidSet
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# ------------------------------------------------------------------------------
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# Public functions, miscellaneous
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# ------------------------------------------------------------------------------
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# Hash set helper
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func hash*(db: AristoDbRef): Hash =
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## Table/KeyedQueue/HashSet mixin
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cast[pointer](db).hash
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# ------------------------------------------------------------------------------
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# Public functions, `dude` related
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# ------------------------------------------------------------------------------
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func isCentre*(db: AristoDbRef): bool =
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## This function returns `true` is the argument `db` is the centre (see
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## comments on `reCentre()` for details.)
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##
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db.dudes.isNil or db.dudes.centre == db
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func getCentre*(db: AristoDbRef): AristoDbRef =
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## Get the centre descriptor among all other descriptors accessing the same
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## backend database (see comments on `reCentre()` for details.)
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##
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if db.dudes.isNil: db else: db.dudes.centre
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proc reCentre*(db: AristoDbRef): Result[void,AristoError] =
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## Re-focus the `db` argument descriptor so that it becomes the centre.
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## Nothing is done if the `db` descriptor is the centre, already.
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##
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## With several descriptors accessing the same backend database there is a
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## single one that has write permission for the backend (regardless whether
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## there is a backend, at all.) The descriptor entity with write permission
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## is called *the centre*.
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##
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## After invoking `reCentre()`, the argument database `db` can only be
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## destructed by `finish()` which also destructs all other descriptors
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## accessing the same backend database. Descriptors where `isCentre()`
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## returns `false` must be single destructed with `forget()`.
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##
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if not db.dudes.isNil:
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db.dudes.centre = db
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ok()
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proc fork*(
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db: AristoDbRef;
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noTopLayer = false;
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noFilter = false;
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): Result[AristoDbRef,AristoError] =
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## This function creates a new empty descriptor accessing the same backend
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## (if any) database as the argument `db`. This new descriptor joins the
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## list of descriptors accessing the same backend database.
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##
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## After use, any unused non centre descriptor should be destructed via
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## `forget()`. Not doing so will not only hold memory ressources but might
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## also cost computing ressources for maintaining and updating backend
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## filters when writing to the backend database .
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##
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## If the argument `noFilter` is set `true` the function will fork directly
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## off the backend database and ignore any filter.
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##
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## If the argument `noTopLayer` is set `true` the function will provide an
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## uninitalised and inconsistent (!) descriptor object without top layer.
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## This setting avoids some database lookup for cases where the top layer
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## is redefined anyway.
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##
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# Make sure that there is a dudes list
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if db.dudes.isNil:
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db.dudes = DudesRef(centre: db, peers: @[db].toHashSet)
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let clone = AristoDbRef(
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dudes: db.dudes,
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backend: db.backend)
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if not noFilter:
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clone.balancer = db.balancer # Ref is ok here (filters are immutable)
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if not noTopLayer:
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clone.top = LayerRef.init()
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if not db.balancer.isNil:
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clone.top.delta.vTop = db.balancer.vTop
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else:
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let rc = clone.backend.getTuvFn()
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if rc.isOk:
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clone.top.delta.vTop = rc.value
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elif rc.error != GetTuvNotFound:
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return err(rc.error)
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# Add to peer list of clones
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db.dudes.peers.incl clone
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ok clone
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iterator forked*(db: AristoDbRef): AristoDbRef =
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## Interate over all non centre descriptors (see comments on `reCentre()`
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## for details.)
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if not db.dudes.isNil:
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for dude in db.getCentre.dudes.peers.items:
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if dude != db.dudes.centre:
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yield dude
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func nForked*(db: AristoDbRef): int =
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## Returns the number of non centre descriptors (see comments on `reCentre()`
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## for details.) This function is a fast version of `db.forked.toSeq.len`.
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if not db.dudes.isNil:
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return db.dudes.peers.len - 1
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proc forget*(db: AristoDbRef): Result[void,AristoError] =
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## Destruct the non centre argument `db` descriptor (see comments on
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## `reCentre()` for details.)
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##
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## A non centre descriptor should always be destructed after use (see also
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## comments on `fork()`.)
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##
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if db.isCentre:
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err(DescNotAllowedOnCentre)
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elif db notin db.dudes.peers:
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err(DescStaleDescriptor)
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else:
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db.dudes.peers.excl db # Unlink argument `db` from peers list
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ok()
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proc forgetOthers*(db: AristoDbRef): Result[void,AristoError] =
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## For the centre argument `db` descriptor (see comments on `reCentre()`
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## for details), destruct all other descriptors accessing the same backend.
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##
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if not db.dudes.isNil:
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if db.dudes.centre != db:
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return err(DescMustBeOnCentre)
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db.dudes = DudesRef(nil)
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ok()
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# ------------------------------------------------------------------------------
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# Public helpers
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# ------------------------------------------------------------------------------
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iterator rstack*(db: AristoDbRef): LayerRef =
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# Stack in reverse order
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for i in 0..<db.stack.len:
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yield db.stack[db.stack.len - i - 1]
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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