snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

test/clientconn_test.go

@@ -0,0 +1,197 @@
+/*
+ *
+ * Copyright 2022 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 test
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/connectivity"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/internal/grpcsync"
+	"google.golang.org/grpc/internal/stubserver"
+	"google.golang.org/grpc/internal/testutils"
+	testgrpc "google.golang.org/grpc/interop/grpc_testing"
+	testpb "google.golang.org/grpc/interop/grpc_testing"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/resolver/manual"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+// TestClientConnClose_WithPendingRPC tests the scenario where the channel has
+// not yet received any update from the name resolver and hence RPCs are
+// blocking. The test verifies that closing the ClientConn unblocks the RPC with
+// the expected error code.
+func (s) TestClientConnClose_WithPendingRPC(t *testing.T) {
+	r := manual.NewBuilderWithScheme("whatever")
+	cc, err := grpc.NewClient(r.Scheme()+":///test.server", grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithResolvers(r))
+	if err != nil {
+		t.Fatalf("grpc.NewClient() failed: %v", err)
+	}
+	client := testgrpc.NewTestServiceClient(cc)
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	doneErrCh := make(chan error, 1)
+	go func() {
+		// This RPC would block until the ClientConn is closed, because the
+		// resolver has not provided its first update yet.
+		_, err := client.EmptyCall(ctx, &testpb.Empty{})
+		if status.Code(err) != codes.Canceled || !strings.Contains(err.Error(), "client connection is closing") {
+			doneErrCh <- fmt.Errorf("EmptyCall() = %v, want %s", err, codes.Canceled)
+		}
+		doneErrCh <- nil
+	}()
+
+	// Make sure that there is one pending RPC on the ClientConn before attempting
+	// to close it. If we don't do this, cc.Close() can happen before the above
+	// goroutine gets to make the RPC.
+	for {
+		if err := ctx.Err(); err != nil {
+			t.Fatal(err)
+		}
+		tcs, _ := channelz.GetTopChannels(0, 0)
+		if len(tcs) != 1 {
+			t.Fatalf("there should only be one top channel, not %d", len(tcs))
+		}
+		started := tcs[0].ChannelMetrics.CallsStarted.Load()
+		completed := tcs[0].ChannelMetrics.CallsSucceeded.Load() + tcs[0].ChannelMetrics.CallsFailed.Load()
+		if (started - completed) == 1 {
+			break
+		}
+		time.Sleep(defaultTestShortTimeout)
+	}
+	cc.Close()
+	if err := <-doneErrCh; err != nil {
+		t.Fatal(err)
+	}
+}
+
+type testStatsHandler struct {
+	nameResolutionDelayed bool
+}
+
+// TagRPC is called when an RPC is initiated and allows adding metadata to the
+// context. It checks if the RPC experienced a name resolution delay and
+// updates the handler's state.
+func (h *testStatsHandler) TagRPC(ctx context.Context, rpcInfo *stats.RPCTagInfo) context.Context {
+	h.nameResolutionDelayed = rpcInfo.NameResolutionDelay
+	return ctx
+}
+
+// This method is required to satisfy the stats.Handler interface.
+func (h *testStatsHandler) HandleRPC(_ context.Context, _ stats.RPCStats) {}
+
+// TagConn exists to satisfy stats.Handler.
+func (h *testStatsHandler) TagConn(ctx context.Context, _ *stats.ConnTagInfo) context.Context {
+	return ctx
+}
+
+// HandleConn exists to satisfy stats.Handler.
+func (h *testStatsHandler) HandleConn(_ context.Context, _ stats.ConnStats) {}
+
+// TestClientConnRPC_WithoutNameResolutionDelay verify that if the resolution
+// has already happened once before at the time of making RPC, the name
+// resolution flag is not set indicating there was no delay in name resolution.
+func (s) TestClientConnRPC_WithoutNameResolutionDelay(t *testing.T) {
+	statsHandler := &testStatsHandler{}
+	ss := &stubserver.StubServer{
+		EmptyCallF: func(context.Context, *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
+	if err := ss.Start(nil, grpc.WithStatsHandler(statsHandler)); err != nil {
+		t.Fatalf("Failed to start StubServer: %v", err)
+	}
+	defer ss.Stop()
+
+	rb := manual.NewBuilderWithScheme("instant")
+	rb.InitialState(resolver.State{Addresses: []resolver.Address{{Addr: ss.Address}}})
+	cc := ss.CC
+	defer cc.Close()
+
+	cc.Connect()
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	testutils.AwaitState(ctx, t, cc, connectivity.Ready)
+	client := testgrpc.NewTestServiceClient(cc)
+	// Verify that the RPC succeeds.
+	if _, err := client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
+		t.Fatalf("First RPC failed unexpectedly: %v", err)
+	}
+	// verifying that RPC was not blocked on resolver indicating there was no
+	// delay in name resolution.
+	if statsHandler.nameResolutionDelayed {
+		t.Fatalf("statsHandler.nameResolutionDelayed = %v; want false", statsHandler.nameResolutionDelayed)
+	}
+}
+
+// TestStatsHandlerDetectsResolutionDelay verifies that if this is the
+// first time resolution is happening at the time of making RPC,
+// nameResolutionDelayed flag is set indicating there was a delay in name
+// resolution waiting for resolver to return addresses.
+func (s) TestClientConnRPC_WithNameResolutionDelay(t *testing.T) {
+	resolutionWait := grpcsync.NewEvent()
+	prevHook := internal.NewStreamWaitingForResolver
+	internal.NewStreamWaitingForResolver = func() { resolutionWait.Fire() }
+	defer func() { internal.NewStreamWaitingForResolver = prevHook }()
+
+	ss := &stubserver.StubServer{
+		EmptyCallF: func(context.Context, *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
+	if err := ss.Start(nil); err != nil {
+		t.Fatalf("Failed to start StubServer: %v", err)
+	}
+	defer ss.Stop()
+
+	statsHandler := &testStatsHandler{}
+	rb := manual.NewBuilderWithScheme("delayed")
+	cc, err := grpc.NewClient(rb.Scheme()+":///test.server",
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithResolvers(rb),
+		grpc.WithStatsHandler(statsHandler),
+	)
+	if err != nil {
+		t.Fatalf("grpc.NewClient() failed: %v", err)
+	}
+	defer cc.Close()
+	go func() {
+		<-resolutionWait.Done()
+		rb.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: ss.Address}}})
+	}()
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	client := testgrpc.NewTestServiceClient(cc)
+	if _, err := client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
+		t.Fatalf("EmptyCall RPC failed: %v", err)
+	}
+	if !statsHandler.nameResolutionDelayed {
+		t.Fatalf("statsHandler.nameResolutionDelayed = %v; want true", statsHandler.nameResolutionDelayed)
+	}
+}