master: rewrite the mirror when the topology id changes at the same bound

A same-bound raft apply carrying a new topology id was skipped by the
lastPersistedMaxVolumeId check, leaving the mirrored topology id empty
until the next allocation. Track the mirrored topology id too and
rewrite when either value differs.

weed/topology/max_volume_id_file_test.go

@@ -43,6 +43,27 @@ func TestMaxVolumeIdFileRestoresTopologyId(t *testing.T) {
 	}
 }
 
+func TestMaxVolumeIdFileRewritesOnTopologyIdChange(t *testing.T) {
+	dir := t.TempDir()
+	file := filepath.Join(dir, "max_volume_id")
+
+	topo := NewTopology("topo", nil, 0, 5, false)
+	topo.SetMaxVolumeIdFile(file)
+	if err := topo.PersistMaxVolumeId(needle.VolumeId(7)); err != nil {
+		t.Fatalf("persist: %v", err)
+	}
+	topo.SetTopologyId("cluster-b")
+	if err := topo.PersistMaxVolumeId(needle.VolumeId(7)); err != nil {
+		t.Fatalf("persist same bound with new topology id: %v", err)
+	}
+
+	restarted := NewTopology("topo", nil, 0, 5, false)
+	restarted.SetMaxVolumeIdFile(file)
+	if got := restarted.GetTopologyId(); got != "cluster-b" {
+		t.Fatalf("restored topology id = %q, want cluster-b", got)
+	}
+}
+
 func TestMaxVolumeIdFileMonotonic(t *testing.T) {
 	dir := t.TempDir()
 	file := filepath.Join(dir, "max_volume_id")

weed/topology/topology.go

@@ -87,6 +87,7 @@ type Topology struct {
 	maxVolumeIdFile          string
 	maxVolumeIdFileLock      sync.Mutex
 	lastPersistedMaxVolumeId atomic.Uint32
+	lastPersistedTopologyId  atomic.Value
 }
 
 func NewTopology(id string, seq sequence.Sequencer, volumeSizeLimit uint64, pulse int, replicationAsMin bool) *Topology {
@@ -964,6 +965,7 @@ func (t *Topology) SetMaxVolumeIdFile(file string) {
 		return
 	}
 	t.lastPersistedMaxVolumeId.Store(uint32(cmd.MaxVolumeId))
+	t.lastPersistedTopologyId.Store(cmd.TopologyId)
 	t.UpAdjustMaxVolumeId(cmd.MaxVolumeId)
 	if cmd.TopologyId != "" {
 		t.SetTopologyId(cmd.TopologyId)
@@ -974,19 +976,24 @@ func (t *Topology) SetMaxVolumeIdFile(file string) {
 // leader before a raft apply and by both raft implementations on apply and
 // recovery, so follower mirrors stay current too.
 func (t *Topology) PersistMaxVolumeId(vid needle.VolumeId) error {
-	if t.lastPersistedMaxVolumeId.Load() >= uint32(vid) {
+	topoId := t.GetTopologyId()
+	mirrored := func() bool {
+		return t.lastPersistedMaxVolumeId.Load() >= uint32(vid) && t.lastPersistedTopologyId.Load() == topoId
+	}
+	if mirrored() {
 		return nil
 	}
 	t.maxVolumeIdFileLock.Lock()
 	defer t.maxVolumeIdFileLock.Unlock()
-	if t.lastPersistedMaxVolumeId.Load() >= uint32(vid) {
+	if mirrored() {
 		return nil
 	}
 	if t.maxVolumeIdFile == "" {
 		t.lastPersistedMaxVolumeId.Store(uint32(vid))
+		t.lastPersistedTopologyId.Store(topoId)
 		return nil
 	}
-	b, err := json.Marshal(NewMaxVolumeIdCommand(vid, t.GetTopologyId()))
+	b, err := json.Marshal(NewMaxVolumeIdCommand(vid, topoId))
 	if err != nil {
 		return err
 	}
@@ -1013,5 +1020,6 @@ func (t *Topology) PersistMaxVolumeId(vid needle.VolumeId) error {
 		return err
 	}
 	t.lastPersistedMaxVolumeId.Store(uint32(vid))
+	t.lastPersistedTopologyId.Store(topoId)
 	return nil
 }