handling connection fault on wsrpc LatestReport

.changeset/fast-dolphins-cry.md

@@ -0,0 +1,5 @@
+---
+"chainlink": patch
+---
+
+handle connection timeout on cache path for ws client LatestReport #bugfix

core/services/relay/evm/mercury/wsrpc/cache/cache.go

@@ -50,9 +50,8 @@ type Fetcher interface {
 }
 
 type Client interface {
-	Fetcher
 	ServerURL() string
-	RawClient() pb.MercuryClient
+	RawLatestReport(ctx context.Context, req *pb.LatestReportRequest) (resp *pb.LatestReportResponse, err error)
 }
 
 // Cache is scoped to one particular mercury server
@@ -194,7 +193,7 @@ func (m *memCache) LatestReport(ctx context.Context, req *pb.LatestReportRequest
 	}
 	feedIDHex := mercuryutils.BytesToFeedID(req.FeedId).String()
 	if m.cfg.LatestReportTTL <= 0 {
-		return m.client.RawClient().LatestReport(ctx, req)
+		return m.client.RawLatestReport(ctx, req)
 	}
 	vi, loaded := m.cache.LoadOrStore(feedIDHex, &cacheVal{
 		sync.RWMutex{},
@@ -311,7 +310,7 @@ func (m *memCache) fetch(req *pb.LatestReportRequest, v *cacheVal) {
 		// NOTE: must drop down to RawClient here otherwise we enter an
 		// infinite loop of calling a client that calls back to this same cache
 		// and on and on
-		val, err = m.client.RawClient().LatestReport(ctx, req)
+		val, err = m.client.RawLatestReport(ctx, req)
 		cancel()
 		v.setError(err)
 		if memcacheCtx.Err() != nil {

core/services/relay/evm/mercury/wsrpc/cache/helpers_test.go

@@ -13,7 +13,7 @@ type mockClient struct {
 	err  error
 }
 
-func (m *mockClient) LatestReport(ctx context.Context, req *pb.LatestReportRequest) (resp *pb.LatestReportResponse, err error) {
+func (m *mockClient) RawLatestReport(ctx context.Context, req *pb.LatestReportRequest) (resp *pb.LatestReportResponse, err error) {
 	return m.resp, m.err
 }
 

core/services/relay/evm/mercury/wsrpc/client.go

@@ -302,6 +302,13 @@ func (w *client) handleTimeout(err error) {
 	} else {
 		w.consecutiveTimeoutCnt.Store(0)
 	}
+
+}
+
+func (w *client) RawLatestReport(ctx context.Context, req *pb.LatestReportRequest) (resp *pb.LatestReportResponse, err error) {
+	resp, err = w.rawClient.LatestReport(ctx, req)
+	w.handleTimeout(err)
+	return
 }
 
 func (w *client) LatestReport(ctx context.Context, req *pb.LatestReportRequest) (resp *pb.LatestReportResponse, err error) {
@@ -312,8 +319,7 @@ func (w *client) LatestReport(ctx context.Context, req *pb.LatestReportRequest)
 	}
 	var cached bool
 	if w.cache == nil {
-		resp, err = w.rawClient.LatestReport(ctx, req)
-		w.handleTimeout(err)
+		resp, err = w.RawLatestReport(ctx, req)
 	} else {
 		cached = true
 		resp, err = w.cache.LatestReport(ctx, req)

core/services/relay/evm/mercury/wsrpc/client_test.go

@@ -176,3 +176,65 @@ func Test_Client_LatestReport(t *testing.T) {
 		})
 	}
 }
+
+func Test_Client_RawLatestReport(t *testing.T) {
+	lggr := logger.TestLogger(t)
+	ctx := testutils.Context(t)
+
+	t.Run("sends on reset channel after MaxConsecutiveRequestFailures timed out transmits", func(t *testing.T) {
+		noopCacheSet := newNoopCacheSet()
+		req := &pb.LatestReportRequest{}
+		calls := 0
+		timeoutErr := context.DeadlineExceeded
+		wsrpcClient := &mocks.MockWSRPCClient{
+			LatestReportF: func(ctx context.Context, in *pb.LatestReportRequest) (*pb.LatestReportResponse, error) {
+				calls++
+				return nil, timeoutErr
+			},
+		}
+		conn := &mocks.MockConn{
+			Ready: true,
+		}
+
+		c := newClient(lggr, csakey.KeyV2{}, nil, "", noopCacheSet)
+		c.conn = conn
+		c.rawClient = wsrpcClient
+		require.NoError(t, c.StartOnce("Mock WSRPC Client", func() error { return nil }))
+		for i := 1; i < MaxConsecutiveRequestFailures; i++ {
+			_, err := c.RawLatestReport(ctx, req)
+			require.EqualError(t, err, "context deadline exceeded")
+		}
+		assert.Equal(t, MaxConsecutiveRequestFailures-1, calls)
+		select {
+		case <-c.chResetTransport:
+			t.Fatal("unexpected send on chResetTransport")
+		default:
+		}
+		_, err := c.RawLatestReport(ctx, req)
+		require.EqualError(t, err, "context deadline exceeded")
+		assert.Equal(t, MaxConsecutiveRequestFailures, calls)
+		select {
+		case <-c.chResetTransport:
+		default:
+			t.Fatal("expected send on chResetTransport")
+		}
+
+		t.Run("successful LatestReport resets the counter", func(t *testing.T) {
+			timeoutErr = nil
+			// working LatestReport to reset counter
+			_, err := c.RawLatestReport(ctx, req)
+			require.NoError(t, err)
+			assert.Equal(t, MaxConsecutiveRequestFailures+1, calls)
+			assert.Equal(t, 0, int(c.consecutiveTimeoutCnt.Load()))
+		})
+
+		t.Run("doesn't block in case channel is full", func(t *testing.T) {
+			timeoutErr = context.DeadlineExceeded
+			c.chResetTransport = nil // simulate full channel
+			for i := 0; i < MaxConsecutiveRequestFailures; i++ {
+				_, err := c.RawLatestReport(ctx, req)
+				require.EqualError(t, err, "context deadline exceeded")
+			}
+		})
+	})
+}