Introduce network serial caching in sync fast path, optimize DB reads, and add granular cache invalidation

management/server/store/sql_store.go

@@ -2658,6 +2658,30 @@ func (s *SqlStore) GetAccountNetwork(ctx context.Context, lockStrength LockingSt
 	return accountNetwork.Network, nil
 }
 
+// GetAccountNetworkSerial returns only the network.serial column for an
+// account, avoiding the overhead of materialising the full Network struct
+// (which carries a JSON-serialised CIDR and other columns). Used by the Sync
+// fast path to check whether the peer's cached serial still matches without
+// paying the full-row read cost on contended DBs.
+func (s *SqlStore) GetAccountNetworkSerial(ctx context.Context, lockStrength LockingStrength, accountID string) (uint64, error) {
+	tx := s.db
+	if lockStrength != LockingStrengthNone {
+		tx = tx.Clauses(clause.Locking{Strength: string(lockStrength)})
+	}
+
+	var serial uint64
+	if err := tx.Model(&types.Account{}).
+		Select("network_serial").
+		Where(idQueryCondition, accountID).
+		Take(&serial).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return 0, status.NewAccountNotFoundError(accountID)
+		}
+		return 0, status.Errorf(status.Internal, "issue getting network serial from store: %s", err)
+	}
+	return serial, nil
+}
+
 func (s *SqlStore) GetPeerByPeerPubKey(ctx context.Context, lockStrength LockingStrength, peerKey string) (*nbpeer.Peer, error) {
 	tx := s.db
 	if lockStrength != LockingStrengthNone {

management/server/store/store.go

@@ -188,6 +188,10 @@ type Store interface {
 	GetTakenIPs(ctx context.Context, lockStrength LockingStrength, accountId string) ([]net.IP, error)
 	IncrementNetworkSerial(ctx context.Context, accountId string) error
 	GetAccountNetwork(ctx context.Context, lockStrength LockingStrength, accountId string) (*types.Network, error)
+	// GetAccountNetworkSerial returns only the network.serial column; used by
+	// the Sync fast path to skip the full-row GetAccountNetwork read when all
+	// we need is the serial.
+	GetAccountNetworkSerial(ctx context.Context, lockStrength LockingStrength, accountId string) (uint64, error)
 
 	GetInstallationID() string
 	SaveInstallationID(ctx context.Context, ID string) error

management/server/store/store_mock.go

@@ -1032,6 +1032,21 @@ func (mr *MockStoreMockRecorder) GetAccountNetwork(ctx, lockStrength, accountId
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetAccountNetwork", reflect.TypeOf((*MockStore)(nil).GetAccountNetwork), ctx, lockStrength, accountId)
 }
 
+// GetAccountNetworkSerial mocks base method.
+func (m *MockStore) GetAccountNetworkSerial(ctx context.Context, lockStrength LockingStrength, accountId string) (uint64, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetAccountNetworkSerial", ctx, lockStrength, accountId)
+	ret0, _ := ret[0].(uint64)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// GetAccountNetworkSerial indicates an expected call of GetAccountNetworkSerial.
+func (mr *MockStoreMockRecorder) GetAccountNetworkSerial(ctx, lockStrength, accountId interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetAccountNetworkSerial", reflect.TypeOf((*MockStore)(nil).GetAccountNetworkSerial), ctx, lockStrength, accountId)
+}
+
 // GetAccountNetworks mocks base method.
 func (m *MockStore) GetAccountNetworks(ctx context.Context, lockStrength LockingStrength, accountID string) ([]*types1.Network, error) {
 	m.ctrl.T.Helper()