hot reloading mule

build.bat

@@ -93,6 +93,7 @@ if "%ryan_scratch%"=="1"       %compile%             ..\src\scratch\ryan_scratch
 if "%look_at_raddbg%"=="1"     %compile%             ..\src\scratch\look_at_raddbg.c                              %compile_link% %out%look_at_raddbg.exe
 if "%mule_main%"=="1"          del vc*.pdb mule*.pdb && %cl_release% /c ..\src\mule\mule_inline.cpp && %cl_release% /c ..\src\mule\mule_o2.cpp && %cl_debug% /EHsc ..\src\mule\mule_main.cpp ..\src\mule\mule_c.c mule_inline.obj mule_o2.obj
 if "%mule_module%"=="1"        %compile%             ..\src\mule\mule_module.cpp                                  %compile_link% %link_dll% %out%mule_module.dll
+if "%mule_hotload%"=="1"       %compile% ..\src\mule\mule_hotload_main.c %compile_link% %out%mule_hotload.exe & %compile% ..\src\mule\mule_hotload_module_main.c %compile_link% %link_dll% %out%mule_hotload_module.dll
 popd
 
 :: --- Unset ------------------------------------------------------------------

src/mule/mule_hotload_main.c

@@ -0,0 +1,48 @@
+#include <stdint.h>
+#include <windows.h>
+
+int main(int argc, char **argv)
+{
+  int lib_loaded = 0;
+  HANDLE lib = {0};
+  FILETIME lib_last_filetime = {0};
+  int (*get_number)(void) = 0;
+  for(;;)
+  {
+    //- rjf: hot-load dll
+    {
+      HANDLE file = CreateFileA("mule_hotload_module.dll", GENERIC_READ, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
+      FILETIME modified = {0};
+      if(GetFileTime(file, 0, 0, &modified) &&
+         CompareFileTime(&lib_last_filetime, &modified) == -1)
+      {
+        for(int reloaded = 0; !reloaded;)
+        {
+          if(lib_loaded)
+          {
+            FreeLibrary(lib);
+            lib_loaded = 0;
+          }
+          BOOL copy_worked = CopyFile("mule_hotload_module.dll", "mule_hotload_module_temp.dll", 0);
+          lib = LoadLibraryA("mule_hotload_module_temp.dll");
+          if(lib != INVALID_HANDLE_VALUE)
+          {
+            reloaded = 1;
+            lib_last_filetime = modified;
+            get_number = (int(*)(void))GetProcAddress(lib, "get_number");
+            lib_loaded = 1;
+          }
+        }
+      }
+      CloseHandle(file);
+    }
+    int number = get_number();
+    printf("got a number: %i\n", number);
+    if(number == 0)
+    {
+      break;
+    }
+    Sleep(1000);
+  }
+  return 0;
+}

src/mule/mule_hotload_module_main.c

@@ -0,0 +1,13 @@
+__declspec(dllexport) int
+get_number(void)
+{
+  int sum = 0;
+  for(int i = 0; i < 100; i += 1)
+  {
+    sum += i;
+    sum += i;
+    sum += 1;
+  }
+  sum = 0;
+  return sum;
+}