.

wcfs/wcfs.go

@@ -1370,7 +1370,7 @@ func (wlink *WatchLink) setupWatch(ctx context.Context, foid zodb.Oid, at zodb.T
 
 	// pin all tracked file blocks that were changed (at, head] range
 	for _, δfile := range bfdir.δFtail.SliceByFileRev(f, at, head.zconn.At()) {
-		for _, blk := range δfile.Change {
+		for blk := range δfile.Change {
 			_, already := toPin[blk]
 			if already {
 				continue

wcfs/δbtail.go

@@ -335,6 +335,12 @@ func (δΒtail *ΔBtail) Get(ctx context.Context, root *Tree, key Key, at zodb.T
 	return
 }
 
+// XXX SliceByRev
+
+// XXX
+func (δBtail *ΔBtail) SliceByRootRev(root *Tree, lo, hi zodb.Tid) /*readonly*/[]ΔTree {
+	panic("TODO")
+}
 
 // δ(BTree) notes
 // ==============

wcfs/δftail.go

@@ -72,6 +72,12 @@ type ΔF struct {
 	Change map[*BigFile]SetI64 // file -> δfile (= {}#blk)
 }
 
+// Δfile represents a change to one file.
+type Δfile struct {
+	Rev    zodb.Tid
+	Change SetI64 // changed blocks
+}
+
 // NewΔFtail creates new ΔFtail object.
 //
 // Initial tracked set is empty.
@@ -149,6 +155,24 @@ func (δFtail *ΔFtail) ForgetPast(revCut zodb.Tid) {
 	panic("TODO")
 }
 
+// XXX SliceByRev
+
+// XXX SliceByFileRev
+func (δFtail *ΔFtail) SliceByFileRev(f *BigFile, lo, hi zodb.Tid) /*readonly*/[]Δfile {
+        tail := δFtail.Tail()
+        head := δFtail.Head()
+        if !(tail <= lo && lo <= hi && hi <= head) {
+                panicf("δFtail.SliceByFileRev: invalid query: (%s, %s];  (tail, head] = (%s, %s]", lo, hi, tail, head)
+        }
+
+	// XXX activate zfile?
+	vδT := δFtail.δBtail.SliceByRootRev(f.zfile.blktab, lo, hi)
+
+	_ = vδT
+	panic("TODO")
+
+}
+
 // LastBlkRev returns last revision that changed file[blk] as of @at database state.
 //
 // if exact=False - what is returned is only an upper bound for last block revision.
@@ -164,6 +188,7 @@ func (f *BigFile) LastBlkRev(ctx context.Context, blk int64, at zodb.Tid) (_ zod
 	δFtail := f.head.bfdir.δFtail
 
 	// XXX tabRev -> treeRev ?
+	// XXX activate zfile?
 	zblkOid, ok, tabRev, tabRevExact, err := δFtail.δBtail.Get(ctx, f.zfile.blktab, blk, at)
 	if err != nil {
 		panic(err)
@@ -186,6 +211,3 @@ func (f *BigFile) LastBlkRev(ctx context.Context, blk int64, at zodb.Tid) (_ zod
 		return tabRev, tabRevExact
 	}
 }
-
-// XXX SliceByRev
-// XXX SliceByFileRev