transport: set current timestamp in channelz socket metrics (#9109)

RELEASE NOTES:
- channelz: Fix `LastMessageSentTimestamp` and
`LastMessageReceivedTimestamp` in `SocketMetrics` to contain the correct
timestamp

Author: easwars

internal/transport/http2_server.go

@@ -44,6 +44,7 @@ import (
 	"google.golang.org/grpc/internal/pretty"
 	istatus "google.golang.org/grpc/internal/status"
 	"google.golang.org/grpc/internal/syscall"
+	transportinternal "google.golang.org/grpc/internal/transport/internal"
 	"google.golang.org/grpc/mem"
 
 	"google.golang.org/grpc/codes"
@@ -1448,14 +1449,14 @@ func (t *http2Server) socketMetrics() *channelz.EphemeralSocketMetrics {
 func (t *http2Server) incrMsgSent() {
 	if channelz.IsOn() {
 		t.channelz.SocketMetrics.MessagesSent.Add(1)
-		t.channelz.SocketMetrics.LastMessageSentTimestamp.Add(1)
+		t.channelz.SocketMetrics.LastMessageSentTimestamp.Store(transportinternal.TimeNowFunc())
 	}
 }
 
 func (t *http2Server) incrMsgRecv() {
 	if channelz.IsOn() {
 		t.channelz.SocketMetrics.MessagesReceived.Add(1)
-		t.channelz.SocketMetrics.LastMessageReceivedTimestamp.Add(1)
+		t.channelz.SocketMetrics.LastMessageReceivedTimestamp.Store(transportinternal.TimeNowFunc())
 	}
 }
 

internal/transport/internal/internal.go

@@ -0,0 +1,25 @@
+/*
+ *
+ * Copyright 2026 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package internal contains functionality internal to the transport package.
+package internal
+
+// TimeNowFunc is a variable that can be set to override the default behavior of
+// getting the current time in nanoseconds. It is used in transport code to set
+// channelz timestamps, and is exposed here for testing purposes.
+var TimeNowFunc func() int64

internal/transport/server_metrics_ext_test.go

@@ -0,0 +1,185 @@
+/*
+ *
+ * Copyright 2026 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport_test
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/internal/stubserver"
+	transportinternal "google.golang.org/grpc/internal/transport/internal"
+
+	testgrpc "google.golang.org/grpc/interop/grpc_testing"
+	testpb "google.golang.org/grpc/interop/grpc_testing"
+)
+
+func overrideTimeNowFunc(t *testing.T, f func() int64) {
+	orig := transportinternal.TimeNowFunc
+	transportinternal.TimeNowFunc = f
+	t.Cleanup(func() { transportinternal.TimeNowFunc = orig })
+}
+
+func verifyResultWithDelay(ctx context.Context, f func() (bool, error)) error {
+	var lastErr error
+	for ; ctx.Err() == nil; <-time.After(10 * time.Millisecond) {
+		var ok bool
+		if ok, lastErr = f(); ok {
+			return nil
+		}
+	}
+	return fmt.Errorf("Timeout when waiting for channelz to contain expected data. Last seen error: %v", lastErr)
+}
+
+func (s) TestChannelz_ServerSocketMetricsLastMessageTimestamps(t *testing.T) {
+	channelz.TurnOn()
+	defer internal.ChannelzTurnOffForTesting()
+
+	// Override timeNowFunc for the duration of the test.
+	var curTime atomic.Int64
+	overrideTimeNowFunc(t, func() int64 {
+		curTime.Add(1)
+		return curTime.Load()
+	})
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+
+	// Start a stub server that echoes back messages sent by the client. This
+	// allows us to test both LastMessageReceivedTimestamp and
+	// LastMessageSentTimestamp on the server side.
+	var blockBeforeSend = make(chan struct{}, 1)
+	ss := &stubserver.StubServer{
+		FullDuplexCallF: func(stream testgrpc.TestService_FullDuplexCallServer) error {
+			for {
+				req, err := stream.Recv()
+				if err == io.EOF {
+					return nil
+				}
+				if err != nil {
+					return err
+				}
+				select {
+				case <-blockBeforeSend:
+				case <-ctx.Done():
+					return ctx.Err()
+				}
+				if err := stream.Send(&testpb.StreamingOutputCallResponse{Payload: req.GetPayload()}); err != nil {
+					return err
+				}
+			}
+		},
+	}
+	if err := ss.Start(nil); err != nil {
+		t.Fatalf("Failed to start test server: %v", err)
+	}
+	defer ss.Stop()
+
+	// Wait for the server to be up and registered with channelz.
+	var svrID int64
+	if err := verifyResultWithDelay(ctx, func() (bool, error) {
+		ssrvs, _ := channelz.GetServers(0, 0)
+		for _, s := range ssrvs {
+			for id := range s.ListenSockets() {
+				skt := channelz.GetSocket(id)
+				if skt != nil && skt.LocalAddr.String() == ss.Address {
+					svrID = s.ID
+					return true, nil
+				}
+			}
+		}
+		return false, fmt.Errorf("could not find server with address %s in channelz", ss.Address)
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	stream, err := ss.Client.FullDuplexCall(ctx)
+	if err != nil {
+		t.Fatalf("FullDuplexCall() failed: %v", err)
+	}
+
+	// Wait for the message from the client to be received on the server and
+	// timestamp updated.
+	wantTimestamp := int64(1)
+	if err := stream.Send(&testpb.StreamingOutputCallRequest{}); err != nil {
+		t.Fatalf("stream.Send(_) = %v, want <nil>", err)
+	}
+	if err := verifyResultWithDelay(ctx, func() (bool, error) {
+		ns, _ := channelz.GetServerSockets(svrID, 0, 0)
+		if len(ns) == 0 {
+			return false, fmt.Errorf("no server sockets found")
+		}
+		sktData := &ns[0].SocketMetrics
+		if sktData.MessagesReceived.Load() < 1 {
+			return false, fmt.Errorf("server has not received any messages yet")
+		}
+		if gotTimestamp := sktData.LastMessageReceivedTimestamp.Load(); gotTimestamp != wantTimestamp {
+			return false, fmt.Errorf("LastMessageReceivedTimestamp is %d, want %d", gotTimestamp, wantTimestamp)
+		}
+		return true, nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	blockBeforeSend <- struct{}{}
+
+	// Wait for the message to be sent by the server and timestamp updated.
+	if _, err := stream.Recv(); err != nil {
+		t.Fatalf("stream.Recv() = %v, want <nil>", err)
+	}
+	wantTimestamp = int64(2)
+	if err := verifyResultWithDelay(ctx, func() (bool, error) {
+		ns, _ := channelz.GetServerSockets(svrID, 0, 0)
+		sktData := &ns[0].SocketMetrics
+		if sktData.MessagesSent.Load() == 0 {
+			return false, fmt.Errorf("server has not sent any messages yet")
+		}
+		if gotTimestamp := sktData.LastMessageSentTimestamp.Load(); gotTimestamp != wantTimestamp {
+			return false, fmt.Errorf("LastMessageSentTimestamp = %d, want = %d", gotTimestamp, wantTimestamp)
+		}
+		return true, nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	// Send another message to verify that LastMessageReceivedTimestamp is
+	// updated again.
+	if err := stream.Send(&testpb.StreamingOutputCallRequest{}); err != nil {
+		t.Fatalf("stream.Send(_) = %v, want <nil>", err)
+	}
+	wantTimestamp = int64(3)
+	if err := verifyResultWithDelay(ctx, func() (bool, error) {
+		ns, _ := channelz.GetServerSockets(svrID, 0, 0)
+		sktData := &ns[0].SocketMetrics
+		if sktData.MessagesReceived.Load() < 2 {
+			return false, fmt.Errorf("server has not received second message yet")
+		}
+		if gotTimestamp := sktData.LastMessageReceivedTimestamp.Load(); gotTimestamp != wantTimestamp {
+			return false, fmt.Errorf("LastMessageReceivedTimestamp is %d, want %d", gotTimestamp, wantTimestamp)
+		}
+		return true, nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+}

internal/transport/transport.go

@@ -35,6 +35,7 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/internal/transport/internal"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
@@ -46,6 +47,10 @@ import (
 
 const logLevel = 2
 
+func init() {
+	internal.TimeNowFunc = func() int64 { return time.Now().UnixNano() }
+}
+
 // recvMsg represents the received msg from the transport. All transport
 // protocol specific info has been removed.
 type recvMsg struct {