os0file.h InnoDB should now run with the same binary on Win95 and NT: checks OS version

srv0start.c	InnoDB should now run with the same binary on Win95 and NT: checks OS version

innobase/include/os0file.h

@@ -100,7 +100,17 @@ log. */
 				requests in a batch, and only after that
  				wake the i/o-handler thread; this has
 				effect only in simulated aio */ 
-				
+#define OS_WIN31     1
+#define OS_WIN95     2	
+#define OS_WINNT     3
+
+/***************************************************************************
+Gets the operating system version. Currently works only on Windows. */
+
+ulint
+os_get_os_version(void);
+/*===================*/
+                  /* out: OS_WIN95, OS_WIN31, OS_WINNT (2000 == NT) */
 /********************************************************************
 Opens an existing file or creates a new. */
 

innobase/srv/srv0start.c

@@ -549,11 +549,19 @@ innobase_start_or_create_for_mysql(void)
 	srv_n_file_io_threads = 4;
 #endif
 
-#ifdef WIN_ASYNC_IO
-	/* On NT always use aio */
-	os_aio_use_native_aio = TRUE;
-#endif
+#ifdef __WIN__
+	if (os_get_os_version() == OS_WIN95
+	    || os_get_os_version() == OS_WIN31) {
+	  /* On Win 95, 98, ME, and Win32 subsystem for Windows 3.1 use
+	     simulated aio */
 
+	  os_aio_use_native_aio = FALSE;
+	  srv_n_file_io_threads = 4;
+	} else {
+	  /* On NT and Win 2000 always use aio */
+	  os_aio_use_native_aio = TRUE;
+	}
+#endif
 	if (!os_aio_use_native_aio) {
 		os_aio_init(4 * SRV_N_PENDING_IOS_PER_THREAD
 						* srv_n_file_io_threads,