From e7e615de26b5bf909aea18ef4e5661502fdc0a4b Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Fri, 27 Nov 2020 05:53:54 -0800
Subject: [PATCH] Removed extraneous windows message pumping

Most of the raw input events are dispatched in the main windows message loop. We only dispatch device change messages separately when we need them to be completely up to date.
---
 src/joystick/windows/SDL_rawinputjoystick.c | 58 +++++++--------------
 1 file changed, 20 insertions(+), 38 deletions(-)

diff --git a/src/joystick/windows/SDL_rawinputjoystick.c b/src/joystick/windows/SDL_rawinputjoystick.c
index 7cf836eb0..e3a1ef7d2 100644
--- a/src/joystick/windows/SDL_rawinputjoystick.c
+++ b/src/joystick/windows/SDL_rawinputjoystick.c
@@ -89,10 +89,7 @@ extern HWND SDL_HelperWindow;
 
 static SDL_bool SDL_RAWINPUT_inited = SDL_FALSE;
 static int SDL_RAWINPUT_numjoysticks = 0;
-static SDL_bool SDL_RAWINPUT_need_pump = SDL_TRUE;
 
-static void RAWINPUT_JoystickDetect(void);
-static void RAWINPUT_PumpMessages(void);
 static void RAWINPUT_JoystickClose(SDL_Joystick *joystick);
 
 typedef struct _SDL_RAWINPUT_Device
@@ -611,6 +608,20 @@ RAWINPUT_QuitWindowsGamingInput(RAWINPUT_DeviceContext *ctx)
 
 #endif /* SDL_JOYSTICK_RAWINPUT_WGI */
 
+
+/* Most of the time the raw input messages will get dispatched in the main event loop,
+ * but sometimes we want to get any pending device change messages immediately.
+ */
+static void
+RAWINPUT_GetPendingDeviceChanges(void)
+{
+    MSG msg;
+    while (PeekMessage(&msg, SDL_HelperWindow, WM_INPUT_DEVICE_CHANGE, WM_INPUT_DEVICE_CHANGE, PM_REMOVE)) {
+        TranslateMessage(&msg);
+        DispatchMessage(&msg);
+    }
+}
+
 static int
 RAWINPUT_JoystickInit(void)
 {
@@ -642,8 +653,9 @@ RAWINPUT_JoystickInit(void)
 
     SDL_RAWINPUT_inited = SDL_TRUE;
 
-    RAWINPUT_JoystickDetect();
-    RAWINPUT_PumpMessages();
+    /* Get initial controller connect messages */
+    RAWINPUT_GetPendingDeviceChanges();
+
     return 0;
 }
 
@@ -830,31 +842,6 @@ RAWINPUT_DelDevice(SDL_RAWINPUT_Device *device, SDL_bool send_event)
     }
 }
 
-static void
-RAWINPUT_PumpMessages(void)
-{
-    if (SDL_RAWINPUT_need_pump) {
-        MSG msg;
-        while (PeekMessage(&msg, SDL_HelperWindow, WM_INPUT, WM_INPUT, PM_REMOVE)) {
-            TranslateMessage(&msg);
-            DispatchMessage(&msg);
-        }
-        SDL_RAWINPUT_need_pump = SDL_FALSE;
-    }
-}
-
-static void
-RAWINPUT_UpdateDeviceList(void)
-{
-    MSG msg;
-    /* In theory, want only WM_INPUT_DEVICE_CHANGE messages here, but PeekMessage returns nothing unless you also ask
-       for WM_INPUT */
-    while (PeekMessage(&msg, SDL_HelperWindow, WM_INPUT_DEVICE_CHANGE, WM_INPUT, PM_REMOVE)) {
-        TranslateMessage(&msg);
-        DispatchMessage(&msg);
-    }
-}
-
 static void
 RAWINPUT_PostUpdate(void)
 {
@@ -926,7 +913,7 @@ RAWINPUT_IsDevicePresent(Uint16 vendor_id, Uint16 product_id, Uint16 version)
     SDL_RAWINPUT_Device *device;
 
     /* Make sure the device list is completely up to date when we check for device presence */
-    RAWINPUT_UpdateDeviceList();
+    RAWINPUT_GetPendingDeviceChanges();
 
     device = SDL_RAWINPUT_devices;
     while (device) {
@@ -941,12 +928,7 @@ RAWINPUT_IsDevicePresent(Uint16 vendor_id, Uint16 product_id, Uint16 version)
 static void
 RAWINPUT_JoystickDetect(void)
 {
-    /* Just ensure the window's add/remove messages have been pumped */
-    RAWINPUT_UpdateDeviceList();
-
     RAWINPUT_PostUpdate();
-
-    SDL_RAWINPUT_need_pump = SDL_TRUE;
 }
 
 static SDL_RAWINPUT_Device *
@@ -1674,8 +1656,8 @@ RAWINPUT_UpdateOtherAPIs(SDL_Joystick *joystick)
 static void
 RAWINPUT_JoystickUpdate(SDL_Joystick *joystick)
 {
-    /* Ensure data messages have been pumped */
-    RAWINPUT_PumpMessages();
+    /* The input events have been handled in the main loop message pumping */
+
     RAWINPUT_UpdateOtherAPIs(joystick);
 }