.

wcfs/wcfs.go

@@ -932,7 +932,7 @@ retry:
 		}
 
 		file.size = size
-		bfdir.δFtail.Track(file, -1, sizePath, nil)
+		bfdir.δFtail.Track(ctx, file, -1, sizePath, nil)
 
 		// XXX we can miss a change to file if δblk is not yet tracked
 		//     -> need to update file.rev at read time -> locking=XXX
@@ -1469,7 +1469,7 @@ func (f *BigFile) readPinWatchers(ctx context.Context, blk int64, treepath []btr
 	bfdir := f.head.bfdir
 	δFtail := bfdir.δFtail
 	bfdir.δFmu.Lock()		// XXX locking correct? XXX -> better push down?
-	δFtail.Track(f, blk, treepath, zblk)	// XXX pass in zblk.rev here?
+	δFtail.Track(ctx, f, blk, treepath, zblk)	// XXX pass in zblk.rev here?
 	bfdir.δFmu.Unlock()
 
 	// make sure that file[blk] on clients side stays as of @w.at state.
@@ -2156,7 +2156,7 @@ func (head *Head) bigopen(ctx context.Context, oid zodb.Oid) (_ *BigFile, err er
 	// only head/ needs δFtail, f.δtail and watches.
 	if head.rev == 0 {
 		head.bfdir.δFmu.Lock()	// XXX locking ok?
-		head.bfdir.δFtail.Track(f, -1, sizePath, nil)
+		head.bfdir.δFtail.Track(ctx, f, -1, sizePath, nil)
 		head.bfdir.δFmu.Unlock()
 
 		// FIXME: scan zfile.blktab - so that we can detect all btree changes

wcfs/δbtail.go

@@ -227,8 +227,12 @@ const (
 
 	// XXX TrackMinKey (we don't need it in WCFS)
 )
-// XXX kill keyPresent
-func (δBtail *ΔBtail) Track(key Key, keyPresent bool, path []Node, flags TrackFlags) {	// XXX Tree|Bucket; path[0] = root
+// XXX kill keyPresent?
+// XXX keep in trackedKeys only keys that are not present in btree - i.e. only negative entries
+//     -> this requires to merge δc returned by diffT and adjust bChildren to tail into
+//     -> it will use less memory and offload Track from (re)loading leaf bucket
+//     ... for now we go more simple way
+func (δBtail *ΔBtail) Track(ctx context.Context, key Key, keyPresent bool, path []Node, flags TrackFlags) error {	// XXX Tree|Bucket; path[0] = root
 	l := len(path)
 	if l == 0 {
 		panic("empty path")
@@ -272,8 +276,29 @@ func (δBtail *ΔBtail) Track(key Key, keyPresent bool, path []Node, flags Track
 	// tracked += all keys of leaf bucket for every node up to the root
 	fmt.Printf("  oldTrack: %v  leafBucket: %v\n", oldTrack, leafBucket)
 	if !oldTrack && leafBucket != nil {
+		// activate leaf node to get access to its data
+		if leafBucket.POid() != zodb.InvalidOid {
+			// normal bucket
+			err := leafBucket.PActivate(ctx)
+			if err != nil {
+				return err
+			}
+			defer leafBucket.PDeactivate()
+		} else {
+			// bucket embedded into tree
+			// XXX assert len(path) == 2
+			err := treeRoot.PActivate(ctx)
+			if err != nil {
+				return err
+			}
+			defer treeRoot.PActivate(ctx)
+			// XXX assert len(treeRoot.Entryv()) == 1
+			// XXX assert [0] is Bucket && POid == zodb.InvalidOid
+			leafBucket = treeRoot.Entryv()[0].Child().(*Bucket) // because it is recreated
+		}
+
 		bkeys := SetKey{}
-		for _, __ := range leafBucket.Entryv() {	// XXX activate
+		for _, __ := range leafBucket.Entryv() {
 			bkeys.Add(__.Key())
 		}
 		fmt.Printf("  bkeys: %s\n", bkeys)
@@ -302,6 +327,7 @@ func (δBtail *ΔBtail) Track(key Key, keyPresent bool, path []Node, flags Track
 
 	// XXX update diff	XXX here? or as separate step?
 	// XXX update lastRevOf
+	return nil
 }
 
 // Update updates δB with per-object level ZODB changes.

wcfs/δbtail_test.go

@@ -548,7 +548,7 @@ func xverifyΔBTail1(t *testing.T, subj string, db *zodb.DB, treeRoot zodb.Oid,
 		if k == kInf {
 			trackFlags = TrackMaxKey
 		}
-		δbtail.Track(k, ok, path, trackFlags)
+		err = δbtail.Track(ctx, k, ok, path, trackFlags); X(err)
 
 		kadjTracked.Update(kadj[k])
 	}

wcfs/δftail.go

@@ -136,13 +136,18 @@ func (δFtail *ΔFtail) Tail() zodb.Tid { return δFtail.δBtail.Tail() }
 // XXX text
 //
 // A root can be associated with several files (each provided on different Track call).
-func (δFtail *ΔFtail) Track(file *BigFile, blk int64, path []btree.LONode, zblk zBlk) {
+//
+// XXX try to avoid ctx
+func (δFtail *ΔFtail) Track(ctx context.Context, file *BigFile, blk int64, path []btree.LONode, zblk zBlk) {
 	δbTrackFlags := TrackFlags(0)
 	if blk == -1 {
 		// XXX blk = ∞ ?
 		δbTrackFlags = TrackMaxKey
 	}
-	δFtail.δBtail.Track(blk, zblk != nil, path, δbTrackFlags)
+	err := δFtail.δBtail.Track(ctx, blk, zblk != nil, path, δbTrackFlags)
+	if err != nil {
+		panic(err) // XXX -> error? errctx
+	}
 	root := path[0].(*btree.LOBTree)
 	files, ok := δFtail.fileIdx[root.POid()]
 	if !ok {