test! baseapp: add concurrent test for querying GRPCRouter

Runs 1,000 concurrent requests for baseapp.GRPCQueryRouter,
this test requires that we enable: go test -race.
Runs 2 different scenarios for the same handler:
* same client connection being used concurrently
* unique client connections

Fixes #10324

baseapp/grpcrouter_test.go

@@ -3,6 +3,7 @@ package baseapp_test
 import (
 	"context"
 	"os"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -74,3 +75,98 @@ func TestRegisterQueryServiceTwice(t *testing.T) {
 		)
 	})
 }
+
+// Tests that we don't have data races per
+// https://github.com/cosmos/cosmos-sdk/issues/10324
+// but with the same client connection being used concurrently.
+func TestQueryDataRaces_sameConnectionToSameHandler(t *testing.T) {
+	var mu sync.Mutex
+	var helper *baseapp.QueryServiceTestHelper
+	makeClientConn := func(qr *baseapp.GRPCQueryRouter) *baseapp.QueryServiceTestHelper {
+		mu.Lock()
+		defer mu.Unlock()
+
+		if helper == nil {
+			helper = &baseapp.QueryServiceTestHelper{
+				GRPCQueryRouter: qr,
+				Ctx:             sdk.Context{}.WithContext(context.Background()),
+			}
+		}
+		return helper
+	}
+	testQueryDataRacesSameHandler(t, makeClientConn)
+}
+
+// Tests that we don't have data races per
+// https://github.com/cosmos/cosmos-sdk/issues/10324
+// but with unique client connections requesting from the same handler concurrently.
+func TestQueryDataRaces_uniqueConnectionsToSameHandler(t *testing.T) {
+	// Return a new handler for every single call.
+	testQueryDataRacesSameHandler(t, func(qr *baseapp.GRPCQueryRouter) *baseapp.QueryServiceTestHelper {
+		return &baseapp.QueryServiceTestHelper{
+			GRPCQueryRouter: qr,
+			Ctx:             sdk.Context{}.WithContext(context.Background()),
+		}
+	})
+}
+
+func testQueryDataRacesSameHandler(t *testing.T, makeClientConn func(*baseapp.GRPCQueryRouter) *baseapp.QueryServiceTestHelper) {
+	t.Parallel()
+
+	qr := baseapp.NewGRPCQueryRouter()
+	interfaceRegistry := testdata.NewTestInterfaceRegistry()
+	qr.SetInterfaceRegistry(interfaceRegistry)
+	testdata.RegisterQueryServer(qr, testdata.QueryImpl{})
+
+	// The goal is to invoke the router concurrently and check for any data races.
+	// 0. Run with: go test -race
+	// 1. Synchronize every one of the 1,000 goroutines waiting to all query at the
+	//    same time.
+	// 2. Once the greenlight is given, perform a query through the router.
+	var wg sync.WaitGroup
+	defer wg.Wait()
+
+	greenlight := make(chan bool)
+	n := 1000
+	ready := make(chan bool, n)
+	go func() {
+		for i := 0; i < n; i++ {
+			<-ready
+		}
+		close(greenlight)
+	}()
+
+	for i := 0; i < n; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+
+			// Wait until we get the green light to start.
+			ready <- true
+			<-greenlight
+
+			client := testdata.NewQueryClient(makeClientConn(qr))
+			res, err := client.Echo(context.Background(), &testdata.EchoRequest{Message: "hello"})
+			require.Nil(t, err)
+			require.NotNil(t, res)
+			require.Equal(t, "hello", res.Message)
+
+			require.Panics(t, func() {
+				_, _ = client.Echo(context.Background(), nil)
+			})
+
+			res2, err := client.SayHello(context.Background(), &testdata.SayHelloRequest{Name: "Foo"})
+			require.Nil(t, err)
+			require.NotNil(t, res)
+			require.Equal(t, "Hello Foo!", res2.Greeting)
+
+			spot := &testdata.Dog{Name: "Spot", Size_: "big"}
+			any, err := types.NewAnyWithValue(spot)
+			require.NoError(t, err)
+			res3, err := client.TestAny(context.Background(), &testdata.TestAnyRequest{AnyAnimal: any})
+			require.NoError(t, err)
+			require.NotNil(t, res3)
+			require.Equal(t, spot, res3.HasAnimal.Animal.GetCachedValue())
+		}()
+	}
+}