# 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: AristoDb): VertexID = ## Create a new `VertexID`. Reusable *ID*s are kept in a list where the top ## entry *ID0* has the property that any other *ID* larger *ID0* is also not ## not used on the database. let top = db.top case top.vGen.len: of 0: # Note that `VertexID(1)` is the root of the main trie top.vGen = @[VertexID(3)] result = VertexID(2) of 1: result = top.vGen[^1] top.vGen = @[VertexID(result.uint64 + 1)] else: result = top.vGen[^2] top.vGen[^2] = top.vGen[^1] top.vGen.setLen(top.vGen.len-1) proc vidPeek*(db: AristoDb): 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: AristoDb; 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*(db: AristoDb) = ## Remove redundant items from the recycle queue. All recycled entries are ## typically kept in the queue until the backend database is committed. if 1 < db.top.vGen.len: let lst = db.top.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: db.top.vGen.shallowCopy lst db.top.vGen.setLen(n+1) return # All entries are continuously increasing db.top.vGen = @[lst[0]] proc vidAttach*(db: AristoDb; 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 proc vidAttach*(db: AristoDb; lbl: HashLabel): VertexID {.discardable.} = ## Variant of `vidAttach()` with auto-generated vertex ID result = db.vidFetch db.vidAttach(lbl, result) proc vidRoot*(db: AristoDb; 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 # ------------------------------------------------------------------------------