Small cleanups (#2414)

* remove unnecessary / expensive error checking
* avoid some trivial memory allocs
* work around table move bug

nimbus/db/aristo/aristo_delta.nim

@@ -13,7 +13,7 @@
 ##
 
 import
-  std/[sequtils, tables],
+  std/tables,
   eth/common,
   results,
   ./aristo_desc,

nimbus/db/aristo/aristo_desc/desc_error.nim

@@ -303,7 +303,6 @@ type
     UtilsAccVtxUnsupported
     UtilsAccWrongStorageRoot
     UtilsPayloadTypeUnsupported
-    UtilsStoRootInaccessible
     UtilsStoRootMissing
 
 # End

nimbus/db/aristo/aristo_hashify.nim

@@ -65,7 +65,7 @@ func getOrVoid(tab: Table[VertexID,VertexID]; vid: VertexID): VertexID =
 func hasValue(
     wffTable: Table[VertexID,VertexID];
     vid: VertexID;
-    wff: WidthFirstForest;
+    wff: var WidthFirstForest;
       ): bool =
   ## Helper for efficient `value` access:
   ## ::
@@ -75,9 +75,10 @@ func hasValue(
   ## ::
   ##   vid in wffTable.values.toSeq
   ##
-  for w in wff.rev.getOrVoid vid:
-    if w in wffTable:
-      return true
+  wff.rev.withValue(vid, v):
+    for w in v[]:
+      if w in wffTable:
+        return true
 
 
 proc pedigree(

nimbus/db/aristo/aristo_utils.nim

@@ -184,7 +184,7 @@ proc retrieveStoAccHike*(
   ## vertex and the vertex ID.
   ##
   # Expand vertex path to account leaf
-  let hike = accPath.to(NibblesBuf).hikeUp(VertexID(1), db).valueOr:
+  var hike = accPath.to(NibblesBuf).hikeUp(VertexID(1), db).valueOr:
     return err(UtilsAccInaccessible)
 
   # Extract the account payload fro the leaf
@@ -192,15 +192,8 @@ proc retrieveStoAccHike*(
   if wp.vtx.vType != Leaf:
     return err(UtilsAccPathWithoutLeaf)
   assert wp.vtx.lData.pType == AccountData            # debugging only
-  let acc = wp.vtx.lData.account
 
-  # Check whether storage ID exists, at all
-  if acc.storageID.isValid:
-    # Verify that the storage root `acc.storageID` exists on the databse
-    discard db.getVtxRc(acc.storageID).valueOr:
-      return err(UtilsStoRootInaccessible)
-
-  ok(hike)
+  ok(move(hike))
 
 proc updateAccountForHasher*(
     db: AristoDbRef;                   # Database

nimbus/db/ledger/accounts_ledger.nim

@@ -695,7 +695,9 @@ proc persist*(ac: AccountsLedgerRef,
   if clearCache:
     # This overwrites the cache from the previous persist, providing a crude LRU
     # scheme with little overhead
-    ac.cache = move(ac.savePoint.cache)
+    # TODO https://github.com/nim-lang/Nim/issues/23759
+    swap(ac.cache, ac.savePoint.cache)
+    ac.savePoint.cache.reset()
 
   ac.savePoint.selfDestruct.clear()