report read limit violations on EventDisconnected via ErrReadLimit sentinel

session.go

@@ -19,6 +19,7 @@ import (
 // ----------------------------------------------------------------------------
 
 var ErrConnectionUnavailable = errors.New("connection unavailable")
+var ErrReadLimit = transport.ErrReadLimit
 
 // ----------------------------------------------------------------------------
 // Config
@@ -249,6 +250,8 @@ func (w *session) serve(
 	stopKeepalive, inactive, heartbeat := w.startKeepalive()
 
 	// run session loop
+	var disconnectErr error
+
 session:
 	for {
 		select {
@@ -257,14 +260,13 @@ session:
 
 		case data, ok := <-conn.Incoming():
 			if !ok {
-				var reason error
 				select {
-				case reason = <-conn.Errors():
+				case disconnectErr = <-conn.Errors():
 				default:
-					reason = fmt.Errorf("unknown")
+					disconnectErr = fmt.Errorf("unknown")
 				}
 				if w.logger != nil {
-					w.logger.Info("websocket: closed", "reason", reason)
+					w.logger.Info("websocket: closed", "reason", disconnectErr)
 				}
 				break session
 			}
@@ -297,7 +299,8 @@ session:
 
 	// tear down connection
 	w.conn.Store(nil)
-	pool.Events <- PoolEvent{URL: w.url, Kind: EventDisconnected, At: time.Now()}
+	pool.Events <- PoolEvent{
+		URL: w.url, Kind: EventDisconnected, Err: disconnectErr, At: time.Now()}
 
 	if w.logger != nil {
 		w.logger.Info("disconnected")

session_test.go

@@ -80,6 +80,37 @@ func TestSession(t *testing.T) {
 		}, "expected EventConnected")
 	})
 
+	t.Run("EventDisconnected carries ErrReadLimit when read limit exceeded", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		mockSocket := honeybeetest.NewMockSocket()
+		mockSocket.ReadMessageFunc = func() (int, []byte, error) {
+			return 0, nil, websocket.ErrReadLimit
+		}
+
+		config, _ := NewSessionConfig(
+			WithRetryDisabled(), WithReconnectDelay(0))
+		w := makeSession(t, mockSocket, config, ctx, cancel)
+		_, events, pool := makeSessionContext(t)
+
+		var wg sync.WaitGroup
+		wg.Go(func() {
+			w.Start(pool)
+		})
+
+		honeybeetest.Eventually(t, func() bool {
+			select {
+			case e := <-events:
+				return e.Kind == EventDisconnected &&
+					e.Err != nil &&
+					errors.Is(e.Err, ErrReadLimit)
+			default:
+				return false
+			}
+		}, "expected EventDisconnected with Err matching ErrReadLimit")
+	})
+
 	t.Run("dial failure exhausted - session exits cleanly, no connected/disconnected events", func(t *testing.T) {
 		ctx, cancel := context.WithCancel(context.Background())
 		defer cancel()

transport/connection.go

@@ -27,6 +27,7 @@ var (
 	ErrPeerClosedClean      = errors.New("peer closed connection cleanly")
 	ErrPeerClosedUnexpected = errors.New("peer closed connection unexpectedly")
 	ErrReadError            = errors.New("read error")
+	ErrReadLimit            = errors.New("read limit exceeded")
 )
 
 // ----------------------------------------------------------------------------
@@ -350,8 +351,13 @@ func (c *Connection) classifyCloseError(err error) error {
 			}
 		}
 
+		if errors.Is(err, websocket.ErrReadLimit) {
+			classifiedError = fmt.Errorf("%w: %w: %v",
+				ErrReadError, ErrReadLimit, err)
+		} else {
 			classifiedError = fmt.Errorf("%w: %w", ErrReadError, err)
 		}
+	}
 
 	return classifiedError
 }

transport/connection_test.go

@@ -225,6 +225,51 @@ func TestConnection_Errors(t *testing.T) {
 		}, "expected read error")
 
 	})
+
+	t.Run("read limit exceeded", func(t *testing.T) {
+		mockSocket := honeybeetest.NewMockSocket()
+		mockSocket.ReadMessageFunc = func() (int, []byte, error) {
+			return 0, nil, websocket.ErrReadLimit
+		}
+
+		conn, err := NewConnection(context.Background(), mockSocket, nil, nil)
+		assert.NoError(t, err)
+		defer conn.Close()
+
+		honeybeetest.Eventually(t, func() bool {
+			select {
+			case err := <-conn.Errors():
+				return errors.Is(err, ErrReadLimit) &&
+					errors.Is(err, ErrReadError) &&
+					!errors.Is(err, websocket.ErrReadLimit)
+			default:
+				return false
+			}
+		}, "expected read limit error classified as ErrReadLimit")
+
+	})
+
+	t.Run("generic read error is not a read limit error", func(t *testing.T) {
+		mockSocket := honeybeetest.NewMockSocket()
+		mockSocket.ReadMessageFunc = func() (int, []byte, error) {
+			return 0, nil, io.EOF
+		}
+
+		conn, err := NewConnection(context.Background(), mockSocket, nil, nil)
+		assert.NoError(t, err)
+		defer conn.Close()
+
+		honeybeetest.Eventually(t, func() bool {
+			select {
+			case err := <-conn.Errors():
+				return errors.Is(err, ErrReadError) &&
+					!errors.Is(err, ErrReadLimit)
+			default:
+				return false
+			}
+		}, "expected generic read error without ErrReadLimit")
+
+	})
 }
 
 func TestConnection_Heartbeat(t *testing.T) {