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

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# nimbus-eth1
# Copyright (c) 2021 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.
## Handle vertex IDs on the layered Aristo DB delta architecture
## =============================================================
{.push raises: [].}
import
std/[algorithm, sequtils, tables],
./aristo_desc
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
proc vidFetch*(db: AristoDbRef; pristine = false): VertexID =
## Create a new `VertexID`. Reusable vertex *ID*s are kept in a list where
## the top entry *ID* has the property that any other *ID* larger is also not
## not used on the database.
##
## The function prefers to return recycled vertex *ID*s if there are any.
## When the argument `pristine` is set `true`, the function guarantees to
## return a non-recycled, brand new vertex *ID* which is the preferred mode
## when creating leaf vertices.
let top = db.top
if top.vGen.len == 0:
# Note that `VertexID(1)` is the root of the main trie
top.vGen = @[VertexID(3)]
result = VertexID(2)
elif top.vGen.len == 1 or pristine:
result = top.vGen[^1]
top.vGen[^1] = result + 1
else:
result = top.vGen[^2]
top.vGen[^2] = top.vGen[^1]
top.vGen.setLen(top.vGen.len-1)
proc vidPeek*(db: AristoDbRef): VertexID =
## Like `new()` without consuming this *ID*. It will return the *ID* that
## would be returned by the `new()` function.
case db.top.vGen.len:
of 0:
VertexID(2)
of 1:
db.top.vGen[^1]
else:
db.top.vGen[^2]
proc vidDispose*(db: AristoDbRef; vid: VertexID) =
## Recycle the argument `vtxID` which is useful after deleting entries from
## the vertex table to prevent the `VertexID` type key values small.
if VertexID(1) < vid:
if db.top.vGen.len == 0:
db.top.vGen = @[vid]
else:
let topID = db.top.vGen[^1]
# Only store smaller numbers: all numberts larger than `topID`
# are free numbers
if vid < topID:
db.top.vGen[^1] = vid
db.top.vGen.add topID
proc vidReorg*(vGen: seq[VertexID]): seq[VertexID] =
## Return a compacted version of the argument vertex ID generator state
## `vGen`. The function removes redundant items from the recycle queue.
if 1 < vGen.len:
let lst = vGen.mapIt(uint64(it)).sorted.mapIt(VertexID(it))
for n in (lst.len-1).countDown(1):
if lst[n-1].uint64 + 1 != lst[n].uint64:
# All elements larger than `lst[n-1]` are in increasing order. For
# the last continuously increasing sequence, only the smallest item
# is needed and the rest can be removed
#
# Example:
# ..3, 5, 6, 7 => ..3, 5
# ^
# |
# n
#
if n < lst.len-1:
return lst[0..n]
return vGen
# All entries are continuously increasing
return @[lst[0]]
vGen
proc vidAttach*(db: AristoDbRef; lbl: HashLabel; vid: VertexID) =
## Attach (i.r. register) a Merkle hash key to a vertex ID.
db.top.pAmk[lbl] = vid
db.top.kMap[vid] = lbl
db.top.dirty = true # Modified top level cache
proc vidAttach*(db: AristoDbRef; lbl: HashLabel): VertexID {.discardable.} =
## Variant of `vidAttach()` with auto-generated vertex ID
result = db.vidFetch
db.vidAttach(lbl, result)
proc vidRoot*(db: AristoDbRef; key: HashKey): VertexID {.discardable.} =
## Variant of `vidAttach()` for generating a sub-trie root
result = db.vidFetch
db.vidAttach(HashLabel(root: result, key: key), result)
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------