113 lines
3.9 KiB
Nim
113 lines
3.9 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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## Handle vertex IDs on the layered Aristo DB delta architecture
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## =============================================================
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{.push raises: [].}
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import
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std/[algorithm, sequtils, typetraits],
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"."/[aristo_desc, aristo_layers]
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# ------------------------------------------------------------------------------
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# Public functions
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# ------------------------------------------------------------------------------
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proc vidFetch*(db: AristoDbRef; pristine = false): VertexID =
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## Recycle or create a new `VertexID`. Reusable vertex *ID*s are kept in a
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## list where the top entry *ID* has the property that any other *ID* larger
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## is also not used on the database.
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##
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## The function prefers to return recycled vertex *ID*s if there are any.
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## When the argument `pristine` is set `true`, the function guarantees to
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## return a non-recycled, brand new vertex *ID* which is the preferred mode
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## when creating leaf vertices.
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##
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if db.vGen.len == 0:
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# Note that `VertexID(1)` is the root of the main trie
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db.top.final.vGen = @[VertexID(LEAST_FREE_VID+1)]
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result = VertexID(LEAST_FREE_VID)
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elif db.vGen.len == 1 or pristine:
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result = db.vGen[^1]
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db.top.final.vGen[^1] = result + 1
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else:
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result = db.vGen[^2]
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db.top.final.vGen[^2] = db.top.final.vGen[^1]
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db.top.final.vGen.setLen(db.vGen.len-1)
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doAssert LEAST_FREE_VID <= result.distinctBase
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proc vidPeek*(db: AristoDbRef): VertexID =
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## Like `new()` without consuming this *ID*. It will return the *ID* that
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## would be returned by the `new()` function.
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##
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case db.vGen.len:
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of 0:
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VertexID(LEAST_FREE_VID)
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of 1:
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db.vGen[^1]
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else:
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db.vGen[^2]
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proc vidDispose*(db: AristoDbRef; vid: VertexID) =
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## Recycle the argument `vtxID` which is useful after deleting entries from
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## the vertex table to prevent the `VertexID` type key values small.
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##
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if LEAST_FREE_VID <= vid.distinctBase:
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if db.vGen.len == 0:
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db.top.final.vGen = @[vid]
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else:
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let topID = db.vGen[^1]
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# Only store smaller numbers: all numberts larger than `topID`
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# are free numbers
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if vid < topID:
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db.top.final.vGen[^1] = vid
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db.top.final.vGen.add topID
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proc vidReorg*(vGen: seq[VertexID]): seq[VertexID] =
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## Return a compacted version of the argument vertex ID generator state
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## `vGen`. The function removes redundant items from the recycle queue and
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## orders it in a way so that smaller `VertexID` numbers are re-used first.
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##
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# Apply heuristic test to avoid unnecessary sorting
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var reOrgOk = false
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if 2 < vGen.len and vGen[0] < vGen[^2]:
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if vGen.len < 10:
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reOrgOk = true
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elif vGen[0] < vGen[1] and vGen[^3] < vGen[^2]:
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reOrgOk = true
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if reOrgOk:
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let lst = vGen.mapIt(uint64(it)).sorted(Descending).mapIt(VertexID(it))
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for n in 0 .. lst.len-2:
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if lst[n].uint64 != lst[n+1].uint64 + 1:
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# All elements of the sequence `lst[0]`..`lst[n]` are in decreasing
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# order with distance 1. Only the smallest item is needed and the
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# rest can be removed (as long as distance is 1.)
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#
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# Example:
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# 7, 6, 5, 3.. => 5, 3.. => @[3..] & @[5]
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# ^
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# |
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# n
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#
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return lst[n+1 .. lst.len-1] & @[lst[n]]
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# Entries decrease continuously
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return @[lst[^1]]
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vGen
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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