recursive    bool       `msg:"rec"`
	dataVersion  uint8      `msg:"v"`
}

func (m *metacache) finished() bool {
	return !m.ended.IsZero()
}

// worthKeeping indicates if the cache by itself is worth keeping.
func (m *metacache) worthKeeping() bool {
	if m == nil {
		return false
	}
	cache := m
	switch {
	case !cache.finished() && time.Since(cache.lastUpdate) > metacacheMaxRunningAge:

		t.Run(tt.id, func(t *testing.T) {
			var want bool
			if i >= len(wantResults) {
				t.Logf("no expected result for test #%d", i)
			} else {
				want = wantResults[i]
			}

			got := tt.worthKeeping()
			if got != want {
				t.Errorf("#%d: want %v, got %v", i, want, got)
			}
		})
	}

	// Entries to remove.
	remove := make(map[string]struct{})

	// Test on a copy
	// cleanup is the only one deleting caches.
	caches, _ := b.cloneCaches()

	for id, cache := range caches {
		if !cache.worthKeeping() {
			b.debugf("cache %s not worth keeping", id)
			remove[id] = struct{}{}
			continue
		}
		if cache.id != id {
			logger.Info("cache ID mismatch %s != %s", id, cache.id)
			remove[id] = struct{}{}