rpc: add test for concurrent WSClient access and request IDs generation

pkg/rpc/client/wsclient_test.go

@@ -6,7 +6,10 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"sort"
+	"strconv"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -15,6 +18,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/rpc/request"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/atomic"
 )
 
 func TestWSClientClose(t *testing.T) {
@@ -344,3 +348,96 @@ func TestNewWS(t *testing.T) {
 		require.Error(t, err)
 	})
 }
+
+func TestWSConcurrentAccess(t *testing.T) {
+	var ids struct {
+		lock sync.RWMutex
+		m    map[int]struct{}
+	}
+	ids.m = make(map[int]struct{})
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		if req.URL.Path == "/ws" && req.Method == "GET" {
+			var upgrader = websocket.Upgrader{}
+			ws, err := upgrader.Upgrade(w, req, nil)
+			require.NoError(t, err)
+			for {
+				err = ws.SetReadDeadline(time.Now().Add(2 * time.Second))
+				require.NoError(t, err)
+				_, p, err := ws.ReadMessage()
+				if err != nil {
+					break
+				}
+				r := request.NewIn()
+				err = json.Unmarshal(p, r)
+				if err != nil {
+					t.Fatalf("Cannot decode request body: %s", req.Body)
+				}
+				i, err := strconv.Atoi(string(r.RawID))
+				require.NoError(t, err)
+				ids.lock.Lock()
+				ids.m[i] = struct{}{}
+				ids.lock.Unlock()
+				var response string
+				// Different responses to catch possible unmarshalling errors connected with invalid IDs distribution.
+				switch r.Method {
+				case "getblockcount":
+					response = fmt.Sprintf(`{"id":%s,"jsonrpc":"2.0","result":123}`, r.RawID)
+				case "getversion":
+					response = fmt.Sprintf(`{"id":%s,"jsonrpc":"2.0","result":{"network":42,"tcpport":20332,"wsport":20342,"nonce":2153672787,"useragent":"/NEO-GO:0.73.1-pre-273-ge381358/"}}`, r.RawID)
+				case "getblockhash":
+					response = fmt.Sprintf(`{"id":%s,"jsonrpc":"2.0","result":"0x157ca5e5b8cf8f84c9660502a3270b346011612bded1514a6847f877c433a9bb"}`, r.RawID)
+				}
+				err = ws.SetWriteDeadline(time.Now().Add(2 * time.Second))
+				require.NoError(t, err)
+				err = ws.WriteMessage(1, []byte(response))
+				if err != nil {
+					break
+				}
+			}
+			ws.Close()
+			return
+		}
+	}))
+	t.Cleanup(srv.Close)
+
+	wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
+	require.NoError(t, err)
+	batchCount := 100
+	completed := atomic.NewInt32(0)
+	for i := 0; i < batchCount; i++ {
+		go func() {
+			_, err := wsc.GetBlockCount()
+			require.NoError(t, err)
+			completed.Inc()
+		}()
+		go func() {
+			_, err := wsc.GetBlockHash(123)
+			require.NoError(t, err)
+			completed.Inc()
+		}()
+
+		go func() {
+			_, err := wsc.GetVersion()
+			require.NoError(t, err)
+			completed.Inc()
+		}()
+	}
+	require.Eventually(t, func() bool {
+		return int(completed.Load()) == batchCount*3
+	}, time.Second, 100*time.Millisecond)
+
+	ids.lock.RLock()
+	require.True(t, len(ids.m) > batchCount)
+	idsList := make([]int, 0, len(ids.m))
+	for i := range ids.m {
+		idsList = append(idsList, i)
+	}
+	ids.lock.RUnlock()
+
+	sort.Ints(idsList)
+	require.Equal(t, 1, idsList[0])
+	require.Less(t, idsList[len(idsList)-1],
+		batchCount*3+1) // batchCount*requestsPerBatch+1
+	wsc.Close()
+}