Partial fix for T37604: Deadlock when stopping rendered viewport (Blender Internal)

- Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS macros cannot be used here, because the Py_BEGIN_ALLOW_THREADS causes a crash when quitting Blender.
- The low level function PyEval_ReleaseLock() is used assuming the Python library was built with multi-threads support.

2 files changed, 38 insertions, 0 deletions

diff --git a/source/blender/python/BPY_extern.h b/source/blender/python/BPY_extern.h
index acb1ab2bcd0..697fa915293 100644
--- a/source/blender/python/BPY_extern.h
+++ b/source/blender/python/BPY_extern.h
@@ -60,6 +60,19 @@ void BPY_python_start(int argc, const char **argv);
 void BPY_python_end(void);
 void BPY_python_reset(struct bContext *C);
 
+
+/* global interpreter lock */
+
+typedef void *BPy_ThreadStatePtr;
+
+BPy_ThreadStatePtr BPY_thread_save(void);
+void BPY_thread_restore(BPy_ThreadStatePtr tstate);
+
+/* our own wrappers to Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS */
+#define BPy_BEGIN_ALLOW_THREADS { BPy_ThreadStatePtr _bpy_saved_tstate = BPY_thread_save(); (void)0
+#define BPy_END_ALLOW_THREADS BPY_thread_restore(_bpy_saved_tstate); } (void)0
+
+
 /* 2.5 UI Scripts */
 int		BPY_filepath_exec(struct bContext *C, const char *filepath, struct ReportList *reports);
 int		BPY_text_exec(struct bContext *C, struct Text *text, struct ReportList *reports, const bool do_jump);
diff --git a/source/blender/python/intern/bpy_interface.c b/source/blender/python/intern/bpy_interface.c
index 7a3d56dc56d..9fbad956d6d 100644
--- a/source/blender/python/intern/bpy_interface.c
+++ b/source/blender/python/intern/bpy_interface.c
@@ -408,6 +408,31 @@ void BPY_python_reset(bContext *C)
 	BPY_modules_load_user(C);
 }
 
+/* wrapper functions related to global interpreter lock. these functions
+ * are slightly different from the original Python API, don't throw
+ * SIGABRT even if the thread state is NULL. */
+
+/* analogue of PyEval_SaveThread() */
+BPy_ThreadStatePtr BPY_thread_save(void)
+{
+	PyThreadState *tstate = PyThreadState_Swap(NULL);
+	/* note: tstate can be NULL when quitting Blender */
+
+	if (tstate && PyEval_ThreadsInitialized()) {
+		PyEval_ReleaseLock();
+	}
+
+	return (BPy_ThreadStatePtr)tstate;
+}
+
+/* analogue of PyEval_RestoreThread() */
+void BPY_thread_restore(BPy_ThreadStatePtr tstate)
+{
+	if (tstate) {
+		PyEval_RestoreThread((PyThreadState *)tstate);
+	}
+}
+
 static void python_script_error_jump_text(struct Text *text)
 {
 	int lineno;