X rebuild: tests: Don't access ZODB in xtrackKeys

Use preloaded data, similarly to previous commit.

95s -> 82s.

wcfs/internal/xbtree/δbtail_test.go

@@ -285,6 +285,17 @@ type RBucket struct {
 	kv      map[Key]string // bucket's k->v; values were ZBlk objects whose data is loaded instead.
 }
 
+// Path returns path to this bucket from tree root.
+func (rb *RBucket) Path() []zodb.Oid {
+	path := []zodb.Oid{rb.oid}
+	p := rb.parent
+	for p != nil {
+		path = append([]zodb.Oid{p.oid}, path...)
+		p = p.parent
+	}
+	return path
+}
+
 // RBucketSet represents set of buckets covering whole [-∞,∞) range.
 type RBucketSet []*RBucket // k↑
 
@@ -728,7 +739,7 @@ func xverifyΔBTail_Update1(t *testing.T, subj string, db *zodb.DB, treeRoot zod
 
 	// δbtail @at1 with initial tracked set
 	δbtail := NewΔBtail(t1.at, db)
-	xtrackKeys(δbtail, treeRoot, initialTrackedKeys)
+	xtrackKeys(δbtail, t1, initialTrackedKeys)
 
 	// TrackedδZ = Tracked ^ δZ  (i.e. a tracked node has changed, or its coverage was changed)
 	TrackedδZ = SetKey{}
@@ -1153,7 +1164,7 @@ func xverifyΔBTail_rebuild_TR(t *testing.T, δbtail *ΔBtail, tj *tTreeCommit,
 	ø := PPTreeSubSet{}
 
 	// Track(keys)
-	xtrackKeys(δbtail, treeRoot, keys)
+	xtrackKeys(δbtail, tj, keys)
 
 	subj := fmt.Sprintf("@%s: after Track%v", xat[tj.at], keys)
 	δbtail.assertTrack(t, subj, trackSet, trackNew)
@@ -1221,27 +1232,17 @@ func assertΔTtail(t *testing.T, subj string, δbtail *ΔBtail, tj *tTreeCommit,
 
 // xtrackKeys issues δbtail.Track requests for tree[keys].
 // XXX place
-func xtrackKeys(δbtail *ΔBtail, treeRoot zodb.Oid, keys SetKey) {
+func xtrackKeys(δbtail *ΔBtail, t *tTreeCommit, keys SetKey) {
 	X := exc.Raiseif
-
-	txn, ctx := transaction.New(context.Background())
-	defer txn.Abort()
-
-	zconn, err := δbtail.db.Open(ctx, &zodb.ConnOptions{At: δbtail.Head()});  X(err)
-
-	xtree, err := zgetNodeOrNil(ctx, zconn, treeRoot); X(err)
-	var ztree *Tree // = nil if treeRoot was deleted
-	if xtree != nil {
-		ztree = xtree.(*Tree)
+	head := δbtail.Head()
+	if head != t.at {
+		panicf("BUG: δbtail.head: %s  ; t.at: %s", head, t.at)
 	}
 
 	for k := range keys {
-		if ztree != nil {
-			_, _, 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
+		// NOTE: if tree is deleted - the following adds it to tracked
+		// set with every key being a hole. This aligns with the
+		// following situation
 		//
 		//	T1 -> ø -> T2
 		//
@@ -1249,8 +1250,8 @@ func xtrackKeys(δbtail *ΔBtail, treeRoot zodb.Oid, keys SetKey) {
 		// 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, []zodb.Oid{treeRoot});  X(err)
-		}
+		b := t.xkv.Get(k)
+		err := δbtail.track(k, b.Path()); X(err)
 	}
 }