rpc: make RPC WSClient thread-safe

Add ability to use unique request IDs for RPC requests.

pkg/rpc/client/client.go

@@ -17,6 +17,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/rpc/request"
 	"github.com/nspcc-dev/neo-go/pkg/rpc/response"
 	"github.com/nspcc-dev/neo-go/pkg/util"
+	"go.uber.org/atomic"
 )
 
 const (
@@ -40,6 +41,12 @@ type Client struct {
 	// cache is mostly filled in during Init(), but can also be updated
 	// during regular Client lifecycle.
 	cache cache
+
+	latestReqID *atomic.Uint64
+	// getNextRequestID returns ID to be used for subsequent request creation.
+	// It is defined on Client so that our testing code can override this method
+	// for the sake of more predictable request IDs generation behaviour.
+	getNextRequestID func() uint64
 }
 
 // Options defines options for the RPC client.
@@ -110,12 +117,18 @@ func New(ctx context.Context, endpoint string, opts Options) (*Client, error) {
 		cache: cache{
 			nativeHashes: make(map[string]util.Uint160),
 		},
+		latestReqID: atomic.NewUint64(0),
 	}
+	cl.getNextRequestID = (cl).getRequestID
 	cl.opts = opts
 	cl.requestF = cl.makeHTTPRequest
 	return cl, nil
 }
 
+func (c *Client) getRequestID() uint64 {
+	return c.latestReqID.Inc()
+}
+
 // Init sets magic of the network client connected to, stateRootInHeader option
 // and native NEO, GAS and Policy contracts scripthashes. This method should be
 // called before any header- or block-related requests in order to deserialize
@@ -159,7 +172,7 @@ func (c *Client) performRequest(method string, p request.RawParams, v interface{
 		JSONRPC:   request.JSONRPCVersion,
 		Method:    method,
 		RawParams: p.Values,
-		ID:        1,
+		ID:        c.getNextRequestID(),
 	}
 
 	raw, err := c.requestF(&r)

pkg/rpc/client/rpc_test.go

@@ -1705,6 +1705,7 @@ func TestRPCClients(t *testing.T) {
 		testRPCClient(t, func(ctx context.Context, endpoint string, opts Options) (*Client, error) {
 			c, err := New(ctx, endpoint, opts)
 			require.NoError(t, err)
+			c.getNextRequestID = getTestRequestID
 			require.NoError(t, c.Init())
 			return c, nil
 		})
@@ -1713,6 +1714,7 @@ func TestRPCClients(t *testing.T) {
 		testRPCClient(t, func(ctx context.Context, endpoint string, opts Options) (*Client, error) {
 			wsc, err := NewWS(ctx, httpURLtoWS(endpoint), opts)
 			require.NoError(t, err)
+			wsc.getNextRequestID = getTestRequestID
 			require.NoError(t, wsc.Init())
 			return &wsc.Client, nil
 		})
@@ -1732,6 +1734,7 @@ func testRPCClient(t *testing.T, newClient func(context.Context, string, Options
 					if err != nil {
 						t.Fatal(err)
 					}
+					c.getNextRequestID = getTestRequestID
 
 					actual, err := testCase.invoke(c)
 					if testCase.fails {
@@ -1755,14 +1758,14 @@ func testRPCClient(t *testing.T, newClient func(context.Context, string, Options
 
 		endpoint := srv.URL
 		opts := Options{}
-		c, err := newClient(context.TODO(), endpoint, opts)
-		if err != nil {
-			t.Fatal(err)
-		}
-
 		for _, testCase := range testBatch {
 			t.Run(testCase.name, func(t *testing.T) {
-				_, err := testCase.invoke(c)
+				c, err := newClient(context.TODO(), endpoint, opts)
+				if err != nil {
+					t.Fatal(err)
+				}
+				c.getNextRequestID = getTestRequestID
+				_, err = testCase.invoke(c)
 				assert.Error(t, err)
 			})
 		}
@@ -1878,6 +1881,7 @@ func TestCalculateValidUntilBlock(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	c.getNextRequestID = getTestRequestID
 	require.NoError(t, c.Init())
 
 	validUntilBlock, err := c.CalculateValidUntilBlock()
@@ -1913,6 +1917,7 @@ func TestGetNetwork(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		c.getNextRequestID = getTestRequestID
 		// network was not initialised
 		_, err = c.GetNetwork()
 		require.True(t, errors.Is(err, errNetworkNotInitialized))
@@ -1924,6 +1929,7 @@ func TestGetNetwork(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		c.getNextRequestID = getTestRequestID
 		require.NoError(t, c.Init())
 		m, err := c.GetNetwork()
 		require.NoError(t, err)
@@ -1945,6 +1951,7 @@ func TestUninitedClient(t *testing.T) {
 
 	c, err := New(context.TODO(), endpoint, opts)
 	require.NoError(t, err)
+	c.getNextRequestID = getTestRequestID
 
 	_, err = c.GetBlockByIndex(0)
 	require.Error(t, err)
@@ -1970,3 +1977,7 @@ func newTestNEF(script []byte) nef.File {
 	ne.Checksum = ne.CalculateChecksum()
 	return ne
 }
+
+func getTestRequestID() uint64 {
+	return 1
+}

pkg/rpc/client/wsclient.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"strconv"
 	"sync"
 	"time"
 
@@ -31,14 +32,16 @@ type WSClient struct {
 	// be closed, so make sure to handle this.
 	Notifications chan Notification
 
-	ws        *websocket.Conn
+	ws       *websocket.Conn
-	done      chan struct{}
+	done     chan struct{}
-	responses chan *response.Raw
+	requests chan *request.Raw
-	requests  chan *request.Raw
+	shutdown chan struct{}
-	shutdown  chan struct{}
 
 	subscriptionsLock sync.RWMutex
 	subscriptions     map[string]bool
+
+	respLock     sync.RWMutex
+	respChannels map[uint64]chan *response.Raw
 }
 
 // Notification represents server-generated notification for client subscriptions.
@@ -95,7 +98,7 @@ func NewWS(ctx context.Context, endpoint string, opts Options) (*WSClient, error
 		ws:            ws,
 		shutdown:      make(chan struct{}),
 		done:          make(chan struct{}),
-		responses:     make(chan *response.Raw),
+		respChannels:  make(map[uint64]chan *response.Raw),
 		requests:      make(chan *request.Raw),
 		subscriptions: make(map[string]bool),
 	}
@@ -178,14 +181,27 @@ readloop:
 			resp.JSONRPC = rr.JSONRPC
 			resp.Error = rr.Error
 			resp.Result = rr.Result
-			c.responses <- resp
+			id, err := strconv.Atoi(string(resp.ID))
+			if err != nil {
+				break // Malformed response (invalid response ID).
+			}
+			ch := c.getResponseChannel(uint64(id))
+			if ch == nil {
+				break // Unknown response (unexpected response ID).
+			}
+			ch <- resp
 		} else {
 			// Malformed response, neither valid request, nor valid response.
 			break
 		}
 	}
 	close(c.done)
-	close(c.responses)
+	c.respLock.Lock()
+	for _, ch := range c.respChannels {
+		close(ch)
+	}
+	c.respChannels = nil
+	c.respLock.Unlock()
 	close(c.Notifications)
 }
 
@@ -220,16 +236,41 @@ func (c *WSClient) wsWriter() {
 	}
 }
 
+func (c *WSClient) registerRespChannel(id uint64, ch chan *response.Raw) {
+	c.respLock.Lock()
+	defer c.respLock.Unlock()
+	c.respChannels[id] = ch
+}
+
+func (c *WSClient) unregisterRespChannel(id uint64) {
+	c.respLock.Lock()
+	defer c.respLock.Unlock()
+	if ch, ok := c.respChannels[id]; ok {
+		delete(c.respChannels, id)
+		close(ch)
+	}
+}
+
+func (c *WSClient) getResponseChannel(id uint64) chan *response.Raw {
+	c.respLock.RLock()
+	defer c.respLock.RUnlock()
+	return c.respChannels[id]
+}
+
 func (c *WSClient) makeWsRequest(r *request.Raw) (*response.Raw, error) {
+	ch := make(chan *response.Raw)
+	c.registerRespChannel(r.ID, ch)
+
 	select {
 	case <-c.done:
-		return nil, errors.New("connection lost")
+		return nil, errors.New("connection lost before sending the request")
 	case c.requests <- r:
 	}
 	select {
 	case <-c.done:
-		return nil, errors.New("connection lost")
+		return nil, errors.New("connection lost while waiting for the response")
-	case resp := <-c.responses:
+	case resp := <-ch:
+		c.unregisterRespChannel(r.ID)
 		return resp, nil
 	}
 }

pkg/rpc/client/wsclient_test.go

@@ -45,6 +45,7 @@ func TestWSClientSubscription(t *testing.T) {
 				srv := initTestServer(t, `{"jsonrpc": "2.0", "id": 1, "result": "55aaff00"}`)
 				wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 				require.NoError(t, err)
+				wsc.getNextRequestID = getTestRequestID
 				require.NoError(t, wsc.Init())
 				id, err := f(wsc)
 				require.NoError(t, err)
@@ -58,6 +59,7 @@ func TestWSClientSubscription(t *testing.T) {
 				srv := initTestServer(t, `{"jsonrpc": "2.0", "id": 1, "error":{"code":-32602,"message":"Invalid Params"}}`)
 				wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 				require.NoError(t, err)
+				wsc.getNextRequestID = getTestRequestID
 				require.NoError(t, wsc.Init())
 				_, err = f(wsc)
 				require.Error(t, err)
@@ -107,6 +109,7 @@ func TestWSClientUnsubscription(t *testing.T) {
 			srv := initTestServer(t, rc.response)
 			wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 			require.NoError(t, err)
+			wsc.getNextRequestID = getTestRequestID
 			require.NoError(t, wsc.Init())
 			rc.code(t, wsc)
 		})
@@ -143,6 +146,7 @@ func TestWSClientEvents(t *testing.T) {
 
 	wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 	require.NoError(t, err)
+	wsc.getNextRequestID = getTestRequestID
 	wsc.cache.initDone = true // Our server mock is restricted, so perform initialisation manually.
 	wsc.cache.network = netmode.UnitTestNet
 	for range events {
@@ -167,6 +171,7 @@ func TestWSExecutionVMStateCheck(t *testing.T) {
 	srv := initTestServer(t, `{"jsonrpc": "2.0", "id": 1, "result": "55aaff00"}`)
 	wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 	require.NoError(t, err)
+	wsc.getNextRequestID = getTestRequestID
 	require.NoError(t, wsc.Init())
 	filter := "NONE"
 	_, err = wsc.SubscribeForTransactionExecutions(&filter)
@@ -316,6 +321,7 @@ func TestWSFilteredSubscriptions(t *testing.T) {
 			}))
 			wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 			require.NoError(t, err)
+			wsc.getNextRequestID = getTestRequestID
 			wsc.cache.network = netmode.UnitTestNet
 			c.clientCode(t, wsc)
 			wsc.Close()
@@ -329,6 +335,8 @@ func TestNewWS(t *testing.T) {
 	t.Run("good", func(t *testing.T) {
 		c, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), Options{})
 		require.NoError(t, err)
+		c.getNextRequestID = getTestRequestID
+		c.cache.network = netmode.UnitTestNet
 		require.NoError(t, c.Init())
 	})
 	t.Run("bad URL", func(t *testing.T) {

pkg/rpc/request/types.go

@@ -32,12 +32,12 @@ func NewRawParams(vals ...interface{}) RawParams {
 	return p
 }
 
-// Raw represents JSON-RPC request.
+// Raw represents JSON-RPC request on the Client side.
 type Raw struct {
 	JSONRPC   string        `json:"jsonrpc"`
 	Method    string        `json:"method"`
 	RawParams []interface{} `json:"params"`
-	ID        int           `json:"id"`
+	ID        uint64        `json:"id"`
 }
 
 // Request contains standard JSON-RPC 2.0 request and batch of