80 lines
2.4 KiB
Nim
80 lines
2.4 KiB
Nim
# nimbus-eth1
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# Copyright (c) 2021 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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./aristo_desc
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# ------------------------------------------------------------------------------
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# Public functions
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# ------------------------------------------------------------------------------
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proc vidFetch*(db: AristoDbRef): VertexID =
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## Create a new `VertexID`. Reusable *ID*s are kept in a list where the top
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## entry *ID0* has the property that any other *ID* larger *ID0* is also not
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## not used on the database.
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# Down the rabbit hole of transaction layers
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let xDb = if db.cascaded: db.base else: db
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case xDb.vidGen.len:
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of 0:
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xDb.vidGen = @[2.VertexID]
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result = 1.VertexID
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of 1:
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result = xDb.vidGen[^1]
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xDb.vidGen = @[(result.uint64 + 1).VertexID]
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else:
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result = xDb.vidGen[^2]
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xDb.vidGen[^2] = xDb.vidGen[^1]
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xDb.vidGen.setLen(xDb.vidGen.len-1)
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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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# Down the rabbit hole of transaction layers
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let xDb = if db.cascaded: db.base else: db
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case xDb.vidGen.len:
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of 0:
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1.VertexID
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of 1:
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xDb.vidGen[^1]
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else:
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xDb.vidGen[^2]
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proc vidDispose*(db: AristoDbRef; vtxID: 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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# Down the rabbit hole of transaction layers
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let xDb = if db.cascaded: db.base else: db
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if xDb.vidGen.len == 0:
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xDb.vidGen = @[vtxID]
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else:
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let topID = xDb.vidGen[^1]
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# No need to store smaller numbers: all numberts larger than `topID`
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# are free numbers
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if vtxID < topID:
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xDb.vidGen[^1] = vtxID
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xDb.vidGen.add topID
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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