.

wcfs/internal/xbtree/δbtail.go

@@ -61,7 +61,7 @@ const debugΔBtail = false
 //   .Track(path)	- start tracking tree nodes and keys; root=path[0], keys=path[-1].(lo,hi]
 //
 //   .Update(δZ) -> δB				- update BTree δ tail given raw ZODB changes
-//   .ForgetPast(revCut)			- forget changes past revCut
+//   .ForgetPast(revCut)			- forget changes ≤ revCut
 //   .SliceByRev(lo, hi) -> []δB		- query for all trees changes with rev ∈ (lo, hi]
 //   .SliceByRootRev(root, lo, hi) -> []δT	- query for changes of a tree with rev ∈ (lo, hi]
 //   .GetAt(root, key, at)			- get root[key] @at assuming root[key] ∈ tracked
@@ -92,12 +92,12 @@ type ΔBtail struct {
 	// taken into account, is kept in _ΔTtail.trackNew & co.
 	trackSet blib.PPTreeSubSet
 
-	// set of trees for which .trackNew is non-empty
+	// set of trees for which _ΔTtail.trackNew is non-empty
 	trackNewRoots setOid
 
 	// handle to make connections to access database.
 	// TODO allow client to optionally provide zconnOld/zconnNew on e.g. Update()
-	db *zodb.DB    // to open connections to load new/old tree|buckets
+	db *zodb.DB // to open connections to load new/old tree|buckets
 }
 
 // _ΔTtail represent tail of revisional changes to one BTree.
@@ -128,7 +128,7 @@ type ΔB struct {
 
 // ΔTree describes changes to one BTree in one revision.
 type ΔTree struct {
-	Rev  zodb.Tid
+	Rev zodb.Tid
 	KV  map[Key]ΔValue
 }
 
@@ -237,8 +237,6 @@ func (δBtail *ΔBtail) Track(key Key, nodePath []Node) {
 	// NOTE key not needed for anything besides tracing
 	// (tracking set will be added with all keys, covered by leaf keyrange)
 
-	// XXX assert node.PJar().At() == .Head()
-
 	path := nodePathToPath(nodePath)
 
 	if traceΔBtail {
@@ -248,6 +246,14 @@ func (δBtail *ΔBtail) Track(key Key, nodePath []Node) {
 		tracefΔBtail("trackSet: %s\n", δBtail.trackSet) // XXX locking
 	}
 
+	head := δBtail.Head()
+	for _, node := range nodePath {
+		nodeAt := node.PJar().At()
+		if nodeAt != head {
+			panicf("node.at (@%s)  !=  δBtail.head (@%s)", nodeAt, head)
+		}
+	}
+
 	δBtail.track(key, path)
 }
 

wcfs/internal/zdata/δftail.go

@@ -104,7 +104,7 @@ type setOid = set.Oid
 //   .Track(file, blk, path, zblk)	- add file and block reached via BTree path to tracked set.
 //
 //   .Update(δZ) -> δF				- update files δ tail given raw ZODB changes
-//   .ForgetPast(revCut)			- forget changes past revCut
+//   .ForgetPast(revCut)			- forget changes ≤ revCut
 //   .SliceByRev(lo, hi) -> []δF		- query for all files changes with rev ∈ (lo, hi]
 //   .SliceByFileRev(file, lo, hi) -> []δfile	- query for changes of a file with rev ∈ (lo, hi]
 //   .BlkRevAt(file, #blk, at)			- query for what is last revision that changed