.

wcfs/internal/xbtree/δbtail.go

@@ -228,6 +228,18 @@ func (btail *ΔTail) Update(δZ *zodb.EventCommit) []ΔTree {
 // func (btail *ΔTail) update()
 
 // XXX -> Get(root, key, at) -> (valueOid, rev) ?
+
+// GetAt returns root[key] as of @at database state plus revision that changed it.
+//
+// if revExact=False - rev is upper estimate for the revision.
+//
+// XXX only tracked set?
+//
+// XXX at must ∈ (tail, head]	XXX [tail ?
+func (btail *ΔTail) GetAt(root *Tree, key Key, at zodb.Tid) (value Value, ok bool, rev zodb.Tid, revExact bool) {
+	panic("TODO")
+}
+
 func (btail *ΔTail) LastRevOf(root *Tree, key Key, at zodb.Tid) (_ zodb.Tid, exact bool) {
 /*
 	lastRevOf = btail.lastRevOf[root]

wcfs/δftail.go

@@ -114,7 +114,6 @@ func (δf *ΔFTail) LastRevOf(file *BigFile, blk int64, at zodb.Tid) (_ zodb.Tid
 }
 */
 
-// XXX δB.GetAt(root, key, at)	at ∈ (tail, head]
 
 // LastBlkRev returns last revision that changed file[blk] as of @at database state.
 //
@@ -130,6 +129,7 @@ func (f *BigFile) LastBlkRev(blk int64, at zodb.Tid) (_ zodb.Tid, exact bool) {
 	zblkOid, ok, tabRev, tabRevExact := δf.ΔTail.GetAt(f.zfile.blktab, blk, at)
 
 	// block was removed
+	// XXX or not in tracked set?
 	if !ok {
 		return tabRev, tabRevExact
 	}