hcontrol,mixer: improve callback GIL state handling

Link: #11
Closes: #12
Signed-off-by: Jaroslav Kysela <[email protected]>

Author: perexg

pyalsa/alsahcontrol.c

@@ -1520,19 +1520,18 @@ MOD_INIT(alsahcontrol)
 
 static int element_callback(snd_hctl_elem_t *elem, unsigned int mask)
 {
-	PyThreadState *tstate, *origstate;
 	struct pyalsahcontrolelement *pyhelem;
 	PyObject *o, *t, *r;
 	int res = 0, inside = 1;
+	CALLBACK_VARIABLES;
 
 	if (elem == NULL)
 		return -EINVAL;
 	pyhelem = snd_hctl_elem_get_callback_private(elem);
 	if (pyhelem == NULL || pyhelem->callback == NULL)
 		return -EINVAL;
 
-	tstate = PyThreadState_New(main_interpreter);
-	origstate = PyThreadState_Swap(tstate);
+	CALLBACK_INIT;
 
 	o = PyObject_GetAttr(pyhelem->callback, InternFromString("callback"));
 	if (!o) {
@@ -1570,8 +1569,7 @@ static int element_callback(snd_hctl_elem_t *elem, unsigned int mask)
 		Py_DECREF(o);
 	}
 
-	PyThreadState_Swap(origstate);
-	PyThreadState_Delete(tstate);
+	CALLBACK_DONE;
 
 	return res;
 }

pyalsa/alsamixer.c

@@ -1325,19 +1325,18 @@ MOD_INIT(alsamixer)
 
 static int element_callback(snd_mixer_elem_t *elem, unsigned int mask)
 {
-	PyThreadState *tstate, *origstate;
 	struct pyalsamixerelement *pyelem;
 	PyObject *o, *t, *r;
 	int res = 0, inside = 1;
+	CALLBACK_VARIABLES;
 
 	if (elem == NULL)
 		return -EINVAL;
 	pyelem = snd_mixer_elem_get_callback_private(elem);
 	if (pyelem == NULL || pyelem->callback == NULL)
 		return -EINVAL;
 
-	tstate = PyThreadState_New(main_interpreter);
-	origstate = PyThreadState_Swap(tstate);
+	CALLBACK_INIT;
 
 	o = PyObject_GetAttr(pyelem->callback, InternFromString("callback"));
 	if (!o) {
@@ -1377,8 +1376,7 @@ static int element_callback(snd_mixer_elem_t *elem, unsigned int mask)
 		Py_DECREF(o);
 	}
 
-	PyThreadState_Swap(origstate);
-	PyThreadState_Delete(tstate);
+	CALLBACK_DONE;
 
 	return res;
 }

pyalsa/common.h

@@ -65,6 +65,31 @@
           ob = Py_InitModule3(name, methods, doc);
 #endif
 
+/*
+ *
+ */
+#if PY_MAJOR_VERSION >= 3
+  #define CALLBACK_VARIABLES \
+	PyGILState_STATE __gstate
+  #define CALLBACK_INIT \
+	__gstate = PyGILState_Ensure()
+  #define CALLBACK_DONE \
+	PyGILState_Release(__gstate)
+#else
+  #define CALLBACK_VARIABLES \
+	PyThreadState *__tstate, *__origstate
+  #define CALLBACK_INIT \
+	do { \
+		__tstate = PyThreadState_New(main_interpreter); \
+		__origstate = PyThreadState_Swap(__tstate); \
+	} while (0)
+  #define CALLBACK_DONE \
+	do { \
+		PyThreadState_Swap(origstate); \
+		PyThreadState_Delete(tstate); \
+	} while (0)
+#endif
+
 /*
  *
  */