update the thread priority of the loop on Windows

Author: hajimehoshi

api_wasapi_windows.go

@@ -24,10 +24,14 @@ import (
 )
 
 var (
-	ole32 = windows.NewLazySystemDLL("ole32")
+	kernel32 = windows.NewLazySystemDLL("kernel32")
+	ole32    = windows.NewLazySystemDLL("ole32")
 )
 
 var (
+	procGetCurrentThread  = kernel32.NewProc("GetCurrentThread")
+	procSetThreadPriority = kernel32.NewProc("SetThreadPriority")
+
 	procCoCreateInstance = ole32.NewProc("CoCreateInstance")
 )
 
@@ -49,6 +53,7 @@ const (
 	_SPEAKER_FRONT_CENTER              = 0x4
 	_SPEAKER_FRONT_LEFT                = 0x1
 	_SPEAKER_FRONT_RIGHT               = 0x2
+	_THREAD_PRIORITY_ABOVE_NORMAL      = 1
 	_WAVE_FORMAT_EXTENSIBLE            = 0xfffe
 )
 
@@ -188,6 +193,16 @@ func _CoCreateInstance(rclsid *windows.GUID, pUnkOuter unsafe.Pointer, dwClsCont
 	return v, nil
 }
 
+func _GetCurrentThread() windows.Handle {
+	r, _, _ := procGetCurrentThread.Call()
+	return windows.Handle(uint32(r))
+}
+
+func _SetThreadPriority(hThread windows.Handle, nPriority int) bool {
+	r, _, _ := procSetThreadPriority.Call(uintptr(hThread), uintptr(nPriority))
+	return uint32(r) != 0
+}
+
 type _IAudioClient2 struct {
 	vtbl *_IAudioClient2_Vtbl
 }

driver_wasapi_windows.go

@@ -316,6 +316,8 @@ func (c *wasapiContext) loop() error {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
+	_SetThreadPriority(_GetCurrentThread(), _THREAD_PRIORITY_ABOVE_NORMAL)
+
 	// S_FALSE is returned when CoInitializeEx is nested. This is a successful case.
 	if err := windows.CoInitializeEx(0, windows.COINIT_MULTITHREADED); err != nil && !errors.Is(err, syscall.Errno(windows.S_FALSE)) {
 		c.client.Stop()