.

wcfs/internal/xbtree/treediff.go

@@ -565,10 +565,11 @@ ABcov:
 		}
 	}
 
-	// {} oid -> parent for all nodes in Bv: current and previously expanded - up till top B
-	BtrackSet := PPTreeSubSet{}
+	// {} oid -> nodeInRange for all nodes we've came through in Bv:
+	// current and previously expanded - up till top B
+	BnodeIdx := map[zodb.Oid]*nodeInRange{}
 	if !Bempty {
-		BtrackSet.AddPath(ABpath)
+		BnodeIdx[ABoid] = btop
 	}
 
 	// δtkeycov will be = BAdd \ ADel
@@ -632,7 +633,7 @@ ABcov:
 					// ( this does not give exact answer but should be a reasonable heuristic;
 					//   the diff is the same if heuristic does not work and we
 					//   look into and load more nodes to compute δ )
-					_, found := BtrackSet[acOid]
+					bc, found := BnodeIdx[acOid]
 					if !found {
 						for {
 							blo  := Bv.Get(ac.lo)
@@ -652,11 +653,12 @@ ABcov:
 							}
 
 							bchildren := Bv.Expand(blo)
-							for _, bc := range bchildren {
-									bcOid := bc.node.POid()
-									BtrackSet.AddPath(bc.Path())
-									if acOid == bcOid {
+							for _, bc_ := range bchildren {
+									bc_Oid := bc_.node.POid()
+									BnodeIdx[bc_Oid] = bc_
+									if acOid == bc_Oid {
 										found = true
+										bc = bc_
 									}
 							}
 							if found {
@@ -667,8 +669,8 @@ ABcov:
 					if found {
 						// ac can be skipped
 						// adjust trackSet since path to the node could have changed
-						apath := trackSet.Path(acOid)
-						bpath := BtrackSet.Path(acOid)
+						apath := ac.Path()
+						bpath := bc.Path()
 						if !pathEqual(apath, bpath) {
 							δtrack.Del.AddPath(apath)
 							δtrack.Add.AddPath(bpath)
@@ -681,7 +683,6 @@ ABcov:
 						// adjust δtkeycov only if it was leaf bucket
 						if nc := at.nchild; nc == 0 {
 							ar := KeyRange{ac.lo, ac.hi_}
-							bc := Bv.Get(ac.lo)
 							br := KeyRange{bc.lo, bc.hi_}
 							δtkeycovADel.AddRange(ar)
 							δtkeycovBAdd.AddRange(br)