watchtower+lnrpc: remove AckedUpdates from ClientSession struct

In this commit, we start making use of the new ListClientSession
functional options added in the previous commit. We use the functional
options in order to calculate the max commit heights per channel on the
construction of the tower client. We also use the options to count the
total number of acked and committed updates. With this commit, we are
also able to completely remove the AckedUpdates member of the
ClientSession since it is no longer used anywhere in the code.

watchtower/wtmock/client_db.go

@@ -26,6 +26,7 @@ type ClientDB struct {
 	mu             sync.Mutex
 	summaries      map[lnwire.ChannelID]wtdb.ClientChanSummary
 	activeSessions map[wtdb.SessionID]wtdb.ClientSession
+	ackedUpdates   map[wtdb.SessionID]map[uint16]wtdb.BackupID
 	towerIndex     map[towerPK]wtdb.TowerID
 	towers         map[wtdb.TowerID]*wtdb.Tower
 
@@ -39,6 +40,7 @@ func NewClientDB() *ClientDB {
 	return &ClientDB{
 		summaries:      make(map[lnwire.ChannelID]wtdb.ClientChanSummary),
 		activeSessions: make(map[wtdb.SessionID]wtdb.ClientSession),
+		ackedUpdates:   make(map[wtdb.SessionID]map[uint16]wtdb.BackupID),
 		towerIndex:     make(map[towerPK]wtdb.TowerID),
 		towers:         make(map[wtdb.TowerID]*wtdb.Tower),
 		indexes:        make(map[keyIndexKey]uint32),
@@ -75,7 +77,7 @@ func (m *ClientDB) CreateTower(lnAddr *lnwire.NetAddress) (*wtdb.Tower, error) {
 	} else {
 		towerID = wtdb.TowerID(atomic.AddUint64(&m.nextTowerID, 1))
 		tower = &wtdb.Tower{
-			ID:          wtdb.TowerID(towerID),
+			ID:          towerID,
 			IdentityKey: lnAddr.IdentityKey,
 			Addresses:   []net.Addr{lnAddr.Address},
 		}
@@ -193,7 +195,7 @@ func (m *ClientDB) ListTowers() ([]*wtdb.Tower, error) {
 // MarkBackupIneligible records that particular commit height is ineligible for
 // backup. This allows the client to track which updates it should not attempt
 // to retry after startup.
-func (m *ClientDB) MarkBackupIneligible(chanID lnwire.ChannelID, commitHeight uint64) error {
+func (m *ClientDB) MarkBackupIneligible(_ lnwire.ChannelID, _ uint64) error {
 	return nil
 }
 
@@ -213,9 +215,14 @@ func (m *ClientDB) ListClientSessions(tower *wtdb.TowerID,
 // optional tower ID can be used to filter out any client sessions in the
 // response that do not correspond to this tower.
 func (m *ClientDB) listClientSessions(tower *wtdb.TowerID,
-	_ ...wtdb.ClientSessionListOption) (
+	opts ...wtdb.ClientSessionListOption) (
 	map[wtdb.SessionID]*wtdb.ClientSession, error) {
 
+	cfg := wtdb.NewClientSessionCfg()
+	for _, o := range opts {
+		o(cfg)
+	}
+
 	sessions := make(map[wtdb.SessionID]*wtdb.ClientSession)
 	for _, session := range m.activeSessions {
 		session := session
@@ -224,6 +231,12 @@ func (m *ClientDB) listClientSessions(tower *wtdb.TowerID,
 		}
 		session.Tower = m.towers[session.TowerID]
 		sessions[session.ID] = &session
+
+		if cfg.PerAckedUpdate != nil {
+			for seq, id := range m.ackedUpdates[session.ID] {
+				cfg.PerAckedUpdate(&session, seq, id)
+			}
+		}
 	}
 
 	return sessions, nil
@@ -274,8 +287,8 @@ func (m *ClientDB) CreateClientSession(session *wtdb.ClientSession) error {
 			RewardPkScript:   cloneBytes(session.RewardPkScript),
 		},
 		CommittedUpdates: make([]wtdb.CommittedUpdate, 0),
-		AckedUpdates:     make(map[uint16]wtdb.BackupID),
 	}
+	m.ackedUpdates[session.ID] = make(map[uint16]wtdb.BackupID)
 
 	return nil
 }
@@ -402,7 +415,7 @@ func (m *ClientDB) AckUpdate(id *wtdb.SessionID, seqNum, lastApplied uint16) err
 		updates[len(updates)-1] = wtdb.CommittedUpdate{}
 		session.CommittedUpdates = updates[:len(updates)-1]
 
-		session.AckedUpdates[seqNum] = update.BackupID
+		m.ackedUpdates[*id][seqNum] = update.BackupID
 		session.TowerLastApplied = lastApplied
 
 		m.activeSessions[*id] = session