Recover gamepad reconnect by forcing SDL re-enumeration

app/streaming/input/gamepad.cpp

@@ -24,6 +24,8 @@ static bool isKeyboardMouseInputAllowed()
 // How long between polling the gamepad to send virtual mouse input
 #define MOUSE_EMULATION_POLLING_INTERVAL 50
 
+#define HOTPLUG_REENUMERATION_INTERVAL_MS 2000
+
 // Determines how fast the mouse will move each interval
 #define MOUSE_EMULATION_MOTION_MULTIPLIER 4
 
@@ -99,32 +101,117 @@ SdlInputHandler::ensureStateForGamepad(SDL_JoystickID id)
 
 void SdlInputHandler::pollForMissingGamepads()
 {
+    static uint32_t s_LastForcedReenumerationTick = 0;
+
     SDL_JoystickUpdate();
     SDL_GameControllerUpdate();
 
-    cleanupDetachedGamepads();
+    auto recoverUntrackedGamepads = [this](int joystickCount) {
+        for (int deviceIndex = 0; deviceIndex < joystickCount; deviceIndex++) {
+            if (!SDL_IsGameController(deviceIndex)) {
+                continue;
+            }
 
-    const int joystickCount = SDL_NumJoysticks();
-    for (int deviceIndex = 0; deviceIndex < joystickCount; deviceIndex++) {
-        if (!SDL_IsGameController(deviceIndex)) {
+            SDL_JoystickID jsId = SDL_JoystickGetDeviceInstanceID(deviceIndex);
+            if (jsId < 0 || findStateForGamepad(jsId) != nullptr) {
+                continue;
+            }
+
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                        "Polling recovered missing gamepad add event (device index: %d, instance ID: %d)",
+                        deviceIndex,
+                        jsId);
+
+            SDL_ControllerDeviceEvent controllerEvent = {};
+            controllerEvent.type = SDL_CONTROLLERDEVICEADDED;
+            controllerEvent.which = deviceIndex;
+            handleControllerDeviceEvent(&controllerEvent);
+        }
+    };
+
+    int joystickCount = SDL_NumJoysticks();
+    if (joystickCount != m_LastJoystickCount) {
+        SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                    "Detected joystick count change: %d -> %d",
+                    m_LastJoystickCount,
+                    joystickCount);
+        m_LastJoystickCount = joystickCount;
+    }
+
+    for (int i = 0; i < MAX_GAMEPADS; i++) {
+        GamepadState* state = &m_GamepadState[i];
+        if (state->controller == nullptr) {
             continue;
         }
 
-        SDL_JoystickID jsId = SDL_JoystickGetDeviceInstanceID(deviceIndex);
-        if (jsId < 0 || findStateForGamepad(jsId) != nullptr) {
+        bool presentInDeviceList = false;
+        for (int deviceIndex = 0; deviceIndex < joystickCount; deviceIndex++) {
+            if (SDL_JoystickGetDeviceInstanceID(deviceIndex) == state->jsId) {
+                presentInDeviceList = true;
+                break;
+            }
+        }
+
+        if (presentInDeviceList) {
             continue;
         }
 
         SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
-                    "Polling recovered missing gamepad add event (device index: %d, instance ID: %d)",
-                    deviceIndex,
-                    jsId);
+                    "Polling detected disconnected gamepad instance %d in slot %d; cleaning up",
+                    state->jsId,
+                    i);
 
         SDL_ControllerDeviceEvent controllerEvent = {};
-        controllerEvent.type = SDL_CONTROLLERDEVICEADDED;
-        controllerEvent.which = deviceIndex;
+        controllerEvent.type = SDL_CONTROLLERDEVICEREMOVED;
+        controllerEvent.which = state->jsId;
         handleControllerDeviceEvent(&controllerEvent);
     }
+
+    recoverUntrackedGamepads(joystickCount);
+
+    if (joystickCount == 0) {
+        uint32_t now = SDL_GetTicks();
+        if (SDL_TICKS_PASSED(now, s_LastForcedReenumerationTick + HOTPLUG_REENUMERATION_INTERVAL_MS)) {
+            s_LastForcedReenumerationTick = now;
+
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                        "No joysticks visible; forcing SDL joystick/gamecontroller re-enumeration");
+
+            SDL_QuitSubSystem(SDL_INIT_GAMECONTROLLER);
+            SDL_QuitSubSystem(SDL_INIT_JOYSTICK);
+
+            if (SDL_InitSubSystem(SDL_INIT_JOYSTICK) != 0) {
+                SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                             "SDL_InitSubSystem(SDL_INIT_JOYSTICK) failed during re-enumeration: %s",
+                             SDL_GetError());
+                return;
+            }
+
+            if (SDL_InitSubSystem(SDL_INIT_GAMECONTROLLER) != 0) {
+                SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                             "SDL_InitSubSystem(SDL_INIT_GAMECONTROLLER) failed during re-enumeration: %s",
+                             SDL_GetError());
+                return;
+            }
+
+            MappingManager mappingManager;
+            mappingManager.applyMappings();
+
+            SDL_JoystickUpdate();
+            SDL_GameControllerUpdate();
+
+            joystickCount = SDL_NumJoysticks();
+            if (joystickCount != m_LastJoystickCount) {
+                SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                            "Detected joystick count change after re-enumeration: %d -> %d",
+                            m_LastJoystickCount,
+                            joystickCount);
+                m_LastJoystickCount = joystickCount;
+            }
+
+            recoverUntrackedGamepads(joystickCount);
+        }
+    }
 }
 
 void SdlInputHandler::cleanupDetachedGamepads()