Replace Backend interface with a struct.

Comparisons (like those in DefaultBackendStorage) should be by pointer value.

pkg/server/backend_manager.go

@@ -77,17 +77,7 @@ func GenProxyStrategiesFromStr(proxyStrategies string) ([]ProxyStrategy, error)
 // In the only currently supported case (gRPC), it wraps an
 // agent.AgentService_ConnectServer, provides synchronization and
 // emits common stream metrics.
-type Backend interface {
- Send(p *client.Packet) error
- Recv() (*client.Packet, error)
- Context() context.Context
- GetAgentID() string
- GetAgentIdentifiers() header.Identifiers
-}
-
-var _ Backend = &backend{}
-
-type backend struct {
+type Backend struct {
  sendLock sync.Mutex
  recvLock sync.Mutex
  conn agent.AgentService_ConnectServer
@@ -97,7 +87,7 @@ type backend struct {
  idents header.Identifiers
 }
 
-func (b *backend) Send(p *client.Packet) error {
+func (b *Backend) Send(p *client.Packet) error {
  b.sendLock.Lock()
  defer b.sendLock.Unlock()
 
@@ -110,7 +100,7 @@ func (b *backend) Send(p *client.Packet) error {
  return err
 }
 
-func (b *backend) Recv() (*client.Packet, error) {
+func (b *Backend) Recv() (*client.Packet, error) {
  b.recvLock.Lock()
  defer b.recvLock.Unlock()
 
@@ -126,16 +116,16 @@ func (b *backend) Recv() (*client.Packet, error) {
  return pkt, nil
 }
 
-func (b *backend) Context() context.Context {
+func (b *Backend) Context() context.Context {
  // TODO: does Context require lock protection?
  return b.conn.Context()
 }
 
-func (b *backend) GetAgentID() string {
+func (b *Backend) GetAgentID() string {
  return b.id
 }
 
-func (b *backend) GetAgentIdentifiers() header.Identifiers {
+func (b *Backend) GetAgentIdentifiers() header.Identifiers {
  return b.idents
 }
 
@@ -168,7 +158,7 @@ func getAgentIdentifiers(conn agent.AgentService_ConnectServer) (header.Identifi
  return header.GenAgentIdentifiers(agentIdent[0])
 }
 
-func NewBackend(conn agent.AgentService_ConnectServer) (Backend, error) {
+func NewBackend(conn agent.AgentService_ConnectServer) (*Backend, error) {
  agentID, err := getAgentID(conn)
  if err != nil {
  return nil, err
@@ -177,16 +167,16 @@ func NewBackend(conn agent.AgentService_ConnectServer) (Backend, error) {
  if err != nil {
  return nil, err
  }
- return &backend{conn: conn, id: agentID, idents: agentIdentifiers}, nil
+ return &Backend{conn: conn, id: agentID, idents: agentIdentifiers}, nil
 }
 
 // BackendStorage is an interface to manage the storage of the backend
 // connections, i.e., get, add and remove
 type BackendStorage interface {
  // addBackend adds a backend.
- addBackend(identifier string, idType header.IdentifierType, backend Backend)
+ addBackend(identifier string, idType header.IdentifierType, backend *Backend)
  // removeBackend removes a backend.
- removeBackend(identifier string, idType header.IdentifierType, backend Backend)
+ removeBackend(identifier string, idType header.IdentifierType, backend *Backend)
  // NumBackends returns the number of backends.
  NumBackends() int
 }
@@ -199,11 +189,11 @@ type BackendManager interface {
  // context instead of a request-scoped context, as the backend manager will
  // pick a backend for every tunnel session and each tunnel session may
  // contains multiple requests.
- Backend(ctx context.Context) (Backend, error)
+ Backend(ctx context.Context) (*Backend, error)
  // AddBackend adds a backend.
- AddBackend(backend Backend)
+ AddBackend(backend *Backend)
  // RemoveBackend adds a backend.
- RemoveBackend(backend Backend)
+ RemoveBackend(backend *Backend)
  BackendStorage
  ReadinessManager
 }
@@ -215,18 +205,18 @@ type DefaultBackendManager struct {
  *DefaultBackendStorage
 }
 
-func (dbm *DefaultBackendManager) Backend(_ context.Context) (Backend, error) {
+func (dbm *DefaultBackendManager) Backend(_ context.Context) (*Backend, error) {
  klog.V(5).InfoS("Get a random backend through the DefaultBackendManager")
  return dbm.DefaultBackendStorage.GetRandomBackend()
 }
 
-func (dbm *DefaultBackendManager) AddBackend(backend Backend) {
+func (dbm *DefaultBackendManager) AddBackend(backend *Backend) {
  agentID := backend.GetAgentID()
  klog.V(5).InfoS("Add the agent to DefaultBackendManager", "agentID", agentID)
  dbm.addBackend(agentID, header.UID, backend)
 }
 
-func (dbm *DefaultBackendManager) RemoveBackend(backend Backend) {
+func (dbm *DefaultBackendManager) RemoveBackend(backend *Backend) {
  agentID := backend.GetAgentID()
  klog.V(5).InfoS("Remove the agent from the DefaultBackendManager", "agentID", agentID)
  dbm.removeBackend(agentID, header.UID, backend)
@@ -242,7 +232,7 @@ type DefaultBackendStorage struct {
  //
  // TODO: fix documentation. This is not always agentID, e.g. in
  // the case of DestHostBackendManager.
- backends map[string][]Backend
+ backends map[string][]*Backend
  // agentID is tracked in this slice to enable randomly picking an
  // agentID in the Backend() method. There is no reliable way to
  // randomly pick a key from a map (in this case, the backends) in
@@ -272,7 +262,7 @@ func NewDefaultBackendStorage(idTypes []header.IdentifierType) *DefaultBackendSt
  // no agent ever successfully connects.
  metrics.Metrics.SetBackendCount(0)
  return &DefaultBackendStorage{
- backends: make(map[string][]Backend),
+ backends: make(map[string][]*Backend),
  random: rand.New(rand.NewSource(time.Now().UnixNano())),
  idTypes: idTypes,
  } /* #nosec G404 */
@@ -283,7 +273,7 @@ func containIDType(idTypes []header.IdentifierType, idType header.IdentifierType
 }
 
 // addBackend adds a backend.
-func (s *DefaultBackendStorage) addBackend(identifier string, idType header.IdentifierType, backend Backend) {
+func (s *DefaultBackendStorage) addBackend(identifier string, idType header.IdentifierType, backend *Backend) {
  if !containIDType(s.idTypes, idType) {
  klog.V(4).InfoS("fail to add backend", "backend", identifier, "error", &ErrWrongIDType{idType, s.idTypes})
  return
@@ -302,7 +292,7 @@ func (s *DefaultBackendStorage) addBackend(identifier string, idType header.Iden
  s.backends[identifier] = append(s.backends[identifier], backend)
  return
  }
- s.backends[identifier] = []Backend{backend}
+ s.backends[identifier] = []*Backend{backend}
  metrics.Metrics.SetBackendCount(len(s.backends))
  s.agentIDs = append(s.agentIDs, identifier)
  if idType == header.DefaultRoute {
@@ -311,7 +301,7 @@ func (s *DefaultBackendStorage) addBackend(identifier string, idType header.Iden
 }
 
 // removeBackend removes a backend.
-func (s *DefaultBackendStorage) removeBackend(identifier string, idType header.IdentifierType, backend Backend) {
+func (s *DefaultBackendStorage) removeBackend(identifier string, idType header.IdentifierType, backend *Backend) {
  if !containIDType(s.idTypes, idType) {
  klog.ErrorS(&ErrWrongIDType{idType, s.idTypes}, "fail to remove backend")
  return
@@ -390,7 +380,7 @@ func ignoreNotFound(err error) error {
 }
 
 // GetRandomBackend returns a random backend connection from all connected agents.
-func (s *DefaultBackendStorage) GetRandomBackend() (Backend, error) {
+func (s *DefaultBackendStorage) GetRandomBackend() (*Backend, error) {
  s.mu.Lock()
  defer s.mu.Unlock()
  if len(s.backends) == 0 {

pkg/server/backend_manager_test.go

@@ -119,7 +119,7 @@ func TestDefaultBackendManager_AddRemoveBackends(t *testing.T) {
 
  p.AddBackend(backend1)
  p.RemoveBackend(backend1)
- expectedBackends := make(map[string][]Backend)
+ expectedBackends := make(map[string][]*Backend)
  expectedAgentIDs := []string{}
  expectedDefaultRouteAgentIDs := []string(nil)
  if e, a := expectedBackends, p.backends; !reflect.DeepEqual(e, a) {
@@ -143,7 +143,7 @@ func TestDefaultBackendManager_AddRemoveBackends(t *testing.T) {
  p.RemoveBackend(backend22)
  p.RemoveBackend(backend2)
  p.RemoveBackend(backend1)
- expectedBackends = map[string][]Backend{
+ expectedBackends = map[string][]*Backend{
  "agent1": {backend12},
  "agent3": {backend3},
  }
@@ -174,7 +174,7 @@ func TestDefaultRouteBackendManager_AddRemoveBackends(t *testing.T) {
 
  p.AddBackend(backend1)
  p.RemoveBackend(backend1)
- expectedBackends := make(map[string][]Backend)
+ expectedBackends := make(map[string][]*Backend)
  expectedAgentIDs := []string{}
  expectedDefaultRouteAgentIDs := []string{}
  if e, a := expectedBackends, p.backends; !reflect.DeepEqual(e, a) {
@@ -199,7 +199,7 @@ func TestDefaultRouteBackendManager_AddRemoveBackends(t *testing.T) {
  p.RemoveBackend(backend2)
  p.RemoveBackend(backend1)
 
- expectedBackends = map[string][]Backend{
+ expectedBackends = map[string][]*Backend{
  "agent1": {backend12},
  "agent3": {backend3},
  }
@@ -231,7 +231,7 @@ func TestDestHostBackendManager_AddRemoveBackends(t *testing.T) {
 
  p.AddBackend(backend1)
  p.RemoveBackend(backend1)
- expectedBackends := make(map[string][]Backend)
+ expectedBackends := make(map[string][]*Backend)
  expectedAgentIDs := []string{}
  expectedDefaultRouteAgentIDs := []string(nil)
  if e, a := expectedBackends, p.backends; !reflect.DeepEqual(e, a) {
@@ -247,7 +247,7 @@ func TestDestHostBackendManager_AddRemoveBackends(t *testing.T) {
  p = NewDestHostBackendManager()
  p.AddBackend(backend1)
 
- expectedBackends = map[string][]Backend{
+ expectedBackends = map[string][]*Backend{
  "localhost": {backend1},
  "1.2.3.4": {backend1},
  "9878::7675:1292:9183:7562": {backend1},
@@ -273,7 +273,7 @@ func TestDestHostBackendManager_AddRemoveBackends(t *testing.T) {
  p.AddBackend(backend2)
  p.AddBackend(backend3)
 
- expectedBackends = map[string][]Backend{
+ expectedBackends = map[string][]*Backend{
  "localhost": {backend1},
  "node1.mydomain.com": {backend1},
  "node2.mydomain.com": {backend3},
@@ -306,7 +306,7 @@ func TestDestHostBackendManager_AddRemoveBackends(t *testing.T) {
  p.RemoveBackend(backend2)
  p.RemoveBackend(backend1)
 
- expectedBackends = map[string][]Backend{
+ expectedBackends = map[string][]*Backend{
  "node2.mydomain.com": {backend3},
  "5.6.7.8": {backend3},
  "::": {backend3},
@@ -328,7 +328,7 @@ func TestDestHostBackendManager_AddRemoveBackends(t *testing.T) {
  }
 
  p.RemoveBackend(backend3)
- expectedBackends = map[string][]Backend{}
+ expectedBackends = map[string][]*Backend{}
  expectedAgentIDs = []string{}
 
  if e, a := expectedBackends, p.backends; !reflect.DeepEqual(e, a) {
@@ -356,7 +356,7 @@ func TestDestHostBackendManager_WithDuplicateIdents(t *testing.T) {
  p.AddBackend(backend2)
  p.AddBackend(backend3)
 
- expectedBackends := map[string][]Backend{
+ expectedBackends := map[string][]*Backend{
  "localhost": {backend1, backend2, backend3},
  "1.2.3.4": {backend1, backend2},
  "5.6.7.8": {backend3},
@@ -389,7 +389,7 @@ func TestDestHostBackendManager_WithDuplicateIdents(t *testing.T) {
  p.RemoveBackend(backend1)
  p.RemoveBackend(backend3)
 
- expectedBackends = map[string][]Backend{
+ expectedBackends = map[string][]*Backend{
  "localhost": {backend2},
  "1.2.3.4": {backend2},
  "9878::7675:1292:9183:7562": {backend2},
@@ -413,7 +413,7 @@ func TestDestHostBackendManager_WithDuplicateIdents(t *testing.T) {
  }
 
  p.RemoveBackend(backend2)
- expectedBackends = map[string][]Backend{}
+ expectedBackends = map[string][]*Backend{}
  expectedAgentIDs = []string{}
 
  if e, a := expectedBackends, p.backends; !reflect.DeepEqual(e, a) {

pkg/server/default_route_backend_manager.go

@@ -36,11 +36,11 @@ func NewDefaultRouteBackendManager() *DefaultRouteBackendManager {
 }
 
 // Backend tries to get a backend that advertises default route, with random selection.
-func (dibm *DefaultRouteBackendManager) Backend(_ context.Context) (Backend, error) {
+func (dibm *DefaultRouteBackendManager) Backend(_ context.Context) (*Backend, error) {
  return dibm.GetRandomBackend()
 }
 
-func (dibm *DefaultRouteBackendManager) AddBackend(backend Backend) {
+func (dibm *DefaultRouteBackendManager) AddBackend(backend *Backend) {
  agentID := backend.GetAgentID()
  agentIdentifiers := backend.GetAgentIdentifiers()
  if agentIdentifiers.DefaultRoute {
@@ -49,7 +49,7 @@ func (dibm *DefaultRouteBackendManager) AddBackend(backend Backend) {
  }
 }
 
-func (dibm *DefaultRouteBackendManager) RemoveBackend(backend Backend) {
+func (dibm *DefaultRouteBackendManager) RemoveBackend(backend *Backend) {
  agentID := backend.GetAgentID()
  agentIdentifiers := backend.GetAgentIdentifiers()
  if agentIdentifiers.DefaultRoute {

pkg/server/desthost_backend_manager.go

@@ -35,7 +35,7 @@ func NewDestHostBackendManager() *DestHostBackendManager {
  []header.IdentifierType{header.IPv4, header.IPv6, header.Host})}
 }
 
-func (dibm *DestHostBackendManager) AddBackend(backend Backend) {
+func (dibm *DestHostBackendManager) AddBackend(backend *Backend) {
  agentIdentifiers := backend.GetAgentIdentifiers()
  for _, ipv4 := range agentIdentifiers.IPv4 {
  klog.V(5).InfoS("Add the agent to DestHostBackendManager", "agent address", ipv4)
@@ -51,7 +51,7 @@ func (dibm *DestHostBackendManager) AddBackend(backend Backend) {
  }
 }
 
-func (dibm *DestHostBackendManager) RemoveBackend(backend Backend) {
+func (dibm *DestHostBackendManager) RemoveBackend(backend *Backend) {
  agentIdentifiers := backend.GetAgentIdentifiers()
  for _, ipv4 := range agentIdentifiers.IPv4 {
  klog.V(5).InfoS("Remove the agent from the DestHostBackendManager", "agentHost", ipv4)
@@ -68,7 +68,7 @@ func (dibm *DestHostBackendManager) RemoveBackend(backend Backend) {
 }
 
 // Backend tries to get a backend associating to the request destination host.
-func (dibm *DestHostBackendManager) Backend(ctx context.Context) (Backend, error) {
+func (dibm *DestHostBackendManager) Backend(ctx context.Context) (*Backend, error) {
  dibm.mu.RLock()
  defer dibm.mu.RUnlock()
  if len(dibm.backends) == 0 {