[3.5] Refactor the keepAliveListener and keepAliveConn

client/pkg/transport/keepalive_listener.go

@@ -21,26 +21,29 @@ import (
 	"time"
 )
 
-type keepAliveConn interface {
-	SetKeepAlive(bool) error
-	SetKeepAlivePeriod(d time.Duration) error
-}
-
 // NewKeepAliveListener returns a listener that listens on the given address.
 // Be careful when wrap around KeepAliveListener with another Listener if TLSInfo is not nil.
 // Some pkgs (like go/http) might expect Listener to return TLSConn type to start TLS handshake.
 // http://tldp.org/HOWTO/TCP-Keepalive-HOWTO/overview.html
+//
+// Note(ahrtr):
+// only `net.TCPConn` supports `SetKeepAlive` and `SetKeepAlivePeriod`
+// by default, so if you want to wrap multiple layers of net.Listener,
+// the `keepaliveListener` should be the one which is closest to the
+// original `net.Listener` implementation, namely `TCPListener`.
 func NewKeepAliveListener(l net.Listener, scheme string, tlscfg *tls.Config) (net.Listener, error) {
+	kal := &keepaliveListener{
+		Listener: l,
+	}
+
 	if scheme == "https" {
 		if tlscfg == nil {
 			return nil, fmt.Errorf("cannot listen on TLS for given listener: KeyFile and CertFile are not presented")
 		}
-		return newTLSKeepaliveListener(l, tlscfg), nil
+		return newTLSKeepaliveListener(kal, tlscfg), nil
 	}
 
-	return &keepaliveListener{
-		Listener: l,
-	}, nil
+	return kal, nil
 }
 
 type keepaliveListener struct{ net.Listener }
@@ -50,13 +53,43 @@ func (kln *keepaliveListener) Accept() (net.Conn, error) {
 	if err != nil {
 		return nil, err
 	}
-	kac := c.(keepAliveConn)
+
+	kac, err := createKeepaliveConn(c)
+	if err != nil {
+		return nil, fmt.Errorf("create keepalive connection failed, %w", err)
+	}
 	// detection time: tcp_keepalive_time + tcp_keepalive_probes + tcp_keepalive_intvl
 	// default on linux:  30 + 8 * 30
 	// default on osx:    30 + 8 * 75
-	kac.SetKeepAlive(true)
-	kac.SetKeepAlivePeriod(30 * time.Second)
-	return c, nil
+	if err := kac.SetKeepAlive(true); err != nil {
+		return nil, fmt.Errorf("SetKeepAlive failed, %w", err)
+	}
+	if err := kac.SetKeepAlivePeriod(30 * time.Second); err != nil {
+		return nil, fmt.Errorf("SetKeepAlivePeriod failed, %w", err)
+	}
+	return kac, nil
+}
+
+func createKeepaliveConn(c net.Conn) (*keepAliveConn, error) {
+	tcpc, ok := c.(*net.TCPConn)
+	if !ok {
+		return nil, ErrNotTCP
+	}
+	return &keepAliveConn{tcpc}, nil
+}
+
+type keepAliveConn struct {
+	*net.TCPConn
+}
+
+// SetKeepAlive sets keepalive
+func (l *keepAliveConn) SetKeepAlive(doKeepAlive bool) error {
+	return l.TCPConn.SetKeepAlive(doKeepAlive)
+}
+
+// SetKeepAlivePeriod sets keepalive period
+func (l *keepAliveConn) SetKeepAlivePeriod(d time.Duration) error {
+	return l.TCPConn.SetKeepAlivePeriod(d)
 }
 
 // A tlsKeepaliveListener implements a network listener (net.Listener) for TLS connections.
@@ -72,12 +105,6 @@ func (l *tlsKeepaliveListener) Accept() (c net.Conn, err error) {
 	if err != nil {
 		return
 	}
-	kac := c.(keepAliveConn)
-	// detection time: tcp_keepalive_time + tcp_keepalive_probes + tcp_keepalive_intvl
-	// default on linux:  30 + 8 * 30
-	// default on osx:    30 + 8 * 75
-	kac.SetKeepAlive(true)
-	kac.SetKeepAlivePeriod(30 * time.Second)
 	c = tls.Server(c, l.config)
 	return c, nil
 }

client/pkg/transport/keepalive_listener_test.go

@@ -40,6 +40,9 @@ func TestNewKeepAliveListener(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unexpected Accept error: %v", err)
 	}
+	if _, ok := conn.(*keepAliveConn); !ok {
+		t.Fatalf("Unexpected conn type: %T, wanted *keepAliveConn", conn)
+	}
 	conn.Close()
 	ln.Close()
 

client/pkg/transport/limit_listen.go

@@ -63,6 +63,9 @@ func (l *limitListenerConn) Close() error {
 	return err
 }
 
+// SetKeepAlive sets keepalive
+//
+// Deprecated: use (*keepAliveConn) SetKeepAlive instead.
 func (l *limitListenerConn) SetKeepAlive(doKeepAlive bool) error {
 	tcpc, ok := l.Conn.(*net.TCPConn)
 	if !ok {
@@ -71,6 +74,9 @@ func (l *limitListenerConn) SetKeepAlive(doKeepAlive bool) error {
 	return tcpc.SetKeepAlive(doKeepAlive)
 }
 
+// SetKeepAlivePeriod sets keepalive period
+//
+// Deprecated: use (*keepAliveConn) SetKeepAlivePeriod instead.
 func (l *limitListenerConn) SetKeepAlivePeriod(d time.Duration) error {
 	tcpc, ok := l.Conn.(*net.TCPConn)
 	if !ok {

client/pkg/transport/listener.go

@@ -68,7 +68,7 @@ func newListener(addr, scheme string, opts ...ListenerOption) (net.Listener, err
 		fallthrough
 	case lnOpts.IsTimeout(), lnOpts.IsSocketOpts():
 		// timeout listener with socket options.
-		ln, err := lnOpts.ListenConfig.Listen(context.TODO(), "tcp", addr)
+		ln, err := newKeepAliveListener(&lnOpts.ListenConfig, addr)
 		if err != nil {
 			return nil, err
 		}
@@ -78,7 +78,7 @@ func newListener(addr, scheme string, opts ...ListenerOption) (net.Listener, err
 			writeTimeout: lnOpts.writeTimeout,
 		}
 	case lnOpts.IsTimeout():
-		ln, err := net.Listen("tcp", addr)
+		ln, err := newKeepAliveListener(nil, addr)
 		if err != nil {
 			return nil, err
 		}
@@ -88,7 +88,7 @@ func newListener(addr, scheme string, opts ...ListenerOption) (net.Listener, err
 			writeTimeout: lnOpts.writeTimeout,
 		}
 	default:
-		ln, err := net.Listen("tcp", addr)
+		ln, err := newKeepAliveListener(nil, addr)
 		if err != nil {
 			return nil, err
 		}
@@ -102,6 +102,19 @@ func newListener(addr, scheme string, opts ...ListenerOption) (net.Listener, err
 	return wrapTLS(scheme, lnOpts.tlsInfo, lnOpts.Listener)
 }
 
+func newKeepAliveListener(cfg *net.ListenConfig, addr string) (ln net.Listener, err error) {
+	if cfg != nil {
+		ln, err = cfg.Listen(context.TODO(), "tcp", addr)
+	} else {
+		ln, err = net.Listen("tcp", addr)
+	}
+	if err != nil {
+		return
+	}
+
+	return NewKeepAliveListener(ln, "tcp", nil)
+}
+
 func wrapTLS(scheme string, tlsinfo *TLSInfo, l net.Listener) (net.Listener, error) {
 	if scheme != "https" && scheme != "unixs" {
 		return l, nil

client/pkg/transport/listener_test.go

@@ -213,6 +213,15 @@ func TestNewListenerWithSocketOpts(t *testing.T) {
 			if !test.expectedErr && err != nil {
 				t.Fatalf("unexpected error: %v", err)
 			}
+
+			if test.scheme == "http" {
+				lnOpts := newListenOpts(test.opts...)
+				if !lnOpts.IsSocketOpts() && !lnOpts.IsTimeout() {
+					if _, ok := ln.(*keepaliveListener); !ok {
+						t.Fatalf("ln: unexpected listener type: %T, wanted *keepaliveListener", ln)
+					}
+				}
+			}
 		})
 	}
 }

server/embed/etcd.go

@@ -650,12 +650,6 @@ func configureClientListeners(cfg *Config) (sctxs map[string]*serveCtx, err erro
 			sctx.l = transport.LimitListener(sctx.l, int(fdLimit-reservedInternalFDNum))
 		}
 
-		if network == "tcp" {
-			if sctx.l, err = transport.NewKeepAliveListener(sctx.l, network, nil); err != nil {
-				return nil, err
-			}
-		}
-
 		defer func(u url.URL) {
 			if err == nil {
 				return