.

wcfs/internal/xbtree/pptreesubset.go

@@ -61,6 +61,11 @@ type nodeInTree struct {
 	// XXX + [lo,hi) range this node is coming under in its parent	XXX -> in its tree ?
 }
 
+// Has returns whether node is in the set.
+func (S PPTreeSubSet) Has(oid zodb.Oid) bool {
+	_, ok := S[oid]
+	return ok
+}
 
 // Path returns path leading to the node specified by oid.
 //

wcfs/internal/xbtree/δbtail.go

@@ -234,8 +234,7 @@ func (δBtail *ΔBtail) Tail() zodb.Tid { return δBtail.δZtail.Tail() }
 // XXX path -> []oid ?
 //
 // XXX catch cycles on add?
-// XXX no need to pass keyPresent since holeIdx was removed
-func (δBtail *ΔBtail) Track(key Key, keyPresent bool, nodePath []Node) error { // XXX Tree|Bucket; path[0] = root
+func (δBtail *ΔBtail) Track(key Key, nodePath []Node) error { // XXX Tree|Bucket; path[0] = root
 
 	path := nodePathToPath(nodePath)
 
@@ -243,13 +242,25 @@ func (δBtail *ΔBtail) Track(key Key, keyPresent bool, nodePath []Node) error {
 	for _, node := range nodePath { pathv = append(pathv, vnode(node)) }
 	tracefΔBtail("\nTrack [%v] %s\n", key, strings.Join(pathv, " -> "))
 
-	return δBtail.track(key, keyPresent, path)
+	return δBtail.track(key, path)
 }
 
-func (δBtail *ΔBtail) track(key Key, keyPresent bool, path []zodb.Oid) error {
+func (δBtail *ΔBtail) track(key Key, path []zodb.Oid) error {
 	// XXX locking
 
 	root := path[0]
+
+	// nothing to do if key is already tracked
+	leaf := path[len(path)-1]
+	if δBtail.trackSet.Has(leaf) {
+		path_ := δBtail.trackSet.Path(leaf)
+		if !pathEqual(path, path_) {
+			panicf("BUG: key %s is already tracked via path=%v\ntrack requests path=%v",  kstr(key), path_, path)
+		}
+		return nil
+	}
+
+	// queue path into trackNew
 	δTtail, ok := δBtail.vδTbyRoot[root]
 	if !ok {
 		δTtail = newΔTtail()
@@ -258,11 +269,6 @@ func (δBtail *ΔBtail) track(key Key, keyPresent bool, path []zodb.Oid) error {
 
 	δBtail.trackNewRoots.Add(root)
 	δTtail.trackNew.AddPath(path)
-
-	// track is track of path[-1]  (i.e. leaf)
-
-	// XXX update diff	XXX here? or as separate step?
-	// XXX update lastRevOf
 	return nil
 }
 
@@ -289,7 +295,7 @@ func (δBtail *ΔBtail) rebuildAll() (err error) {
 // rebuild rebuilds ΔTtail taking trackNew requests into account.
 //
 // It returns set of nodes that must be added to ΔBtail.trackSet to account for
-// keys that becomes tracked. Note: this set is potentially wider compared to .trackNew.
+// keys that becomes tracked. Note: this set is potentially wider compared to what was in .trackNew.
 // XXX place
 func (δTtail *ΔTtail) rebuild(δZtail *zodb.ΔTail, db *zodb.DB) (δtrackSet PPTreeSubSet, err error) {
 	defer xerr.Context(&err, "ΔTtail rebuild")
@@ -351,6 +357,7 @@ func (δTtail *ΔTtail) rebuild(δZtail *zodb.ΔTail, db *zodb.DB) (δtrackSet P
 			}
 
 			// FIXME use δtkeycov to recompute track coverage
+			_ = δtkeycov
 
 			debugfΔBtail("  -> root<%s>  δkv*: %v  δtrack*: %v\n", root, δT, δtrack)
 
@@ -501,6 +508,7 @@ if XXX_killWhenRebuildWorks {
 			δB.ΔByRoot[root] = δT
 			δTtail, ok := δBtail.vδTbyRoot[root]
 			if !ok {
+				// XXX should not happen (only roots requested to be present are present in δ)
 				// this root was not tracked before -> create δTtail for it with empty changes
 				δTtail = newΔTtail()
 				δBtail.vδTbyRoot[root] = δTtail
@@ -514,6 +522,8 @@ if XXX_killWhenRebuildWorks {
 
 		δBtail.trackSet.ApplyΔ(δtrack)
 		δTKeyCov.ByRoot[root] = δtkeycov
+
+		// XXX if δtkeycov != ø  -> rebuild δTtail
 	}
 
 	return δB, δTKeyCov, nil

wcfs/internal/xbtree/δbtail_test.go

@@ -720,8 +720,8 @@ func xverifyΔBTail_Update1(t *testing.T, subj string, db *zodb.DB, treeRoot zod
 
 	for k := range initialTrackedKeys {
 		if ztree != nil {
-			_, ok, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
-			err = δbtail.Track(k, ok, path); X(err)
+			_, _, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
+			err = δbtail.Track(k, path); X(err)
 		} else {
 			// if treeRoot is deleted - add it to tracked set with every key
 			// being a hole. This aligns with the following situation
@@ -732,7 +732,7 @@ func xverifyΔBTail_Update1(t *testing.T, subj string, db *zodb.DB, treeRoot zod
 			// continues to be tracked and all keys migrate to holes in the
 			// tracking set. By aligning initial state to the same as after
 			// T1->ø, we test what will happen on ø->T2.
-			err = δbtail.track(k, false, []zodb.Oid{treeRoot});  X(err)
+			err = δbtail.track(k, []zodb.Oid{treeRoot});  X(err)
 		}
 	}
 
@@ -1108,8 +1108,8 @@ func xverifyΔBTail_rebuild_TR(t *testing.T, db *zodb.DB, δbtail *ΔBtail, tj *
 	xtree, err := zconn.Get(ctx, treeRoot);	 X(err)
 	ztree := xtree.(*Tree)
 	for k := range keys {
-		_, ok, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
-		err = δbtail.Track(k, ok, path);  X(err)
+		_, _, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
+		err = δbtail.Track(k, path);  X(err)
 	}
 
 	δbtail.assertTrack(t, fmt.Sprintf("@%s: after Track%v", xat[tj.at], keys), trackSet, trackNew)
@@ -1218,8 +1218,8 @@ func xverifyΔBTail_GetAt1(t *testing.T, db *zodb.DB, treeRoot zodb.Oid, vt []*t
 	ztree := xtree.(*Tree)
 
 	for k := range keys {
-		_, ok, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
-		err = δbtail.Track(k, ok, path);  X(err)
+		_, _, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
+		err = δbtail.Track(k, path);  X(err)
 	}
 
 	// verify GetAt(k, @at) for all keys and @at