130 lines
4.3 KiB
Nim
130 lines
4.3 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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## Aristo DB -- Patricia Trie layer management
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## ===========================================
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##
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import
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std/[sequtils, tables],
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stew/results,
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"."/[aristo_desc, aristo_get]
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type
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DeltaHistoryRef* = ref object
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## Change history for backend saving
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leafs*: Table[LeafTie,PayloadRef] ## Changed leafs after merge into backend
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# ------------------------------------------------------------------------------
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# Private functions
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# ------------------------------------------------------------------------------
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proc cpy(layer: AristoLayerRef): AristoLayerRef =
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new result
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result[] = layer[]
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# ------------------------------------------------------------------------------
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# Public functions
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# ------------------------------------------------------------------------------
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proc push*(db: var AristoDb) =
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## Save a copy of the current delta state on the stack of non-persistent
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## state layers.
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db.stack.add db.top.cpy
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proc pop*(db: var AristoDb; merge = true): AristoError =
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## Remove the current state later and merge it into the next layer if the
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## argument `merge` is `true`, and discard it otherwise. The next layer then
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## becomes the current state.
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##
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## Note that merging is sort of a virtual action because the top layer has
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## always the full latest non-persistent delta state. This implies that in
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## the case of *merging* just the first parent layer will be discarded.
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##
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if 0 < db.stack.len:
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if not merge:
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# Roll back to parent layer state
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db.top = db.stack[^1]
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db.stack.setLen(db.stack.len-1)
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elif merge:
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# Accept as-is (there is no parent layer)
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discard
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elif db.backend.isNil:
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db.top = AristoLayerRef()
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else:
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# Initialise new top layer from the backend
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let rc = db.backend.getIdgFn()
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if rc.isErr:
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return rc.error
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db.top = AristoLayerRef(vGen: rc.value)
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AristoError(0)
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proc save*(
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db: var AristoDb; # Database to be updated
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clear = true; # Clear current top level cache
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): Result[DeltaHistoryRef,AristoError] =
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## Save top layer into persistent database. There is no check whether the
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## current layer is fully consistent as a Merkle Patricia Tree. It is
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## advised to run `hashify()` on the top layer before calling `save()`.
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##
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## After successful storage, all parent layers are cleared. The top layer
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## is also cleared if the `clear` flag is set `true`.
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##
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## Upon successful return, the previous state of the backend data is returned
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## relative to the changes made.
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##
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let be = db.backend
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if be.isNil:
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return err(SaveBackendMissing)
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let hst = DeltaHistoryRef() # Change history
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# Record changed `Leaf` nodes into the history table
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for (lky,vid) in db.top.lTab.pairs:
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if vid.isValid:
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# Get previous payload for this vertex
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let rc = db.getVtxBackend vid
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if rc.isErr:
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if rc.error != GetVtxNotFound:
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return err(rc.error) # Stop
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hst.leafs[lky] = PayloadRef(nil) # So this is a new leaf vertex
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elif rc.value.vType == Leaf:
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hst.leafs[lky] = rc.value.lData # Record previous payload
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else:
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hst.leafs[lky] = PayloadRef(nil) # Was re-puropsed as leaf vertex
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else:
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hst.leafs[lky] = PayloadRef(nil) # New leaf vertex
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# Save structural and other table entries
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let txFrame = be.putBegFn()
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be.putVtxFn(txFrame, db.top.sTab.pairs.toSeq)
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be.putKeyFn(txFrame, db.top.kMap.pairs.toSeq.mapIt((it[0],it[1].key)))
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be.putIdgFn(txFrame, db.top.vGen)
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let w = be.putEndFn txFrame
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if w != AristoError(0):
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return err(w)
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# Delete stack and clear top
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db.stack.setLen(0)
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if clear:
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db.top = AristoLayerRef(vGen: db.top.vGen)
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ok hst
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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