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authorChristian Tismer <tismer@stackless.com>2018-03-23 19:54:42 +0100
committerChristian Tismer <tismer@stackless.com>2018-04-19 11:20:51 +0000
commita89690409972501741c846ac8ad4a499f2982809 (patch)
tree7684abfa34b4c9aa66ab317452da37ccc1f8f31e /sources/shiboken2/libshiboken/qapp_macro.cpp
parent4023ab3862eee7ca3084dd83ca76fba11b5db46b (diff)
fix more qApp crashes
When building PySide with a debug Python, a lot more problems become visible. They were triggered by some malicious ordering of the shutdown code, which must come *after* the refcounts of the variables are adjusted. The initial issue PYSIDE-585 was caused because the shutdown code is not only used for every created Q*Application, but also for the module shutdown, which deletes qApp_contents too often. Instead of special-casing that or adding some refcount, it was much more intuitive in that context to set qApp_content's refcount to the same value as Py_None, which also is not supposed to be garbage collected. Btw., the reason for the error message is that Py_None has it, too. When we set qApp_content's type to Py_None's type, it inherits the protection code that prevents someone from garbage collecting Py_None. Task-number: PYSIDE-585 Change-Id: I4af9de1192730f06054a5aca099a32e2392e367d Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Diffstat (limited to 'sources/shiboken2/libshiboken/qapp_macro.cpp')
-rw-r--r--sources/shiboken2/libshiboken/qapp_macro.cpp24
1 files changed, 16 insertions, 8 deletions
diff --git a/sources/shiboken2/libshiboken/qapp_macro.cpp b/sources/shiboken2/libshiboken/qapp_macro.cpp
index 9b940aaa..e3f23de4 100644
--- a/sources/shiboken2/libshiboken/qapp_macro.cpp
+++ b/sources/shiboken2/libshiboken/qapp_macro.cpp
@@ -105,7 +105,14 @@ reset_qApp_var()
return 0;
}
-
+/*
+ * Note:
+ * The PYSIDE-585 problem was that shutdown is called one more often
+ * than Q*Application is created. We could special-case that last
+ * shutdown or add a refcount, initially, but actually it was easier
+ * and more intuitive in that context to make the refcount of
+ * qApp_content equal to the refcount of Py_None.
+ */
PyObject *
MakeSingletonQAppWrapper(PyTypeObject *type)
{
@@ -132,15 +139,16 @@ MakeSingletonQAppWrapper(PyTypeObject *type)
// Debug mode showed that we need to do more than just remove the
// reference. To keep everything in the right order, it is easiest
// to do a full shutdown, using QtCore.__moduleShutdown().
+ // restore the "None-state"
PyObject *__moduleShutdown = PyDict_GetItemString(qApp_moduledicts[1],
"__moduleShutdown");
- if (__moduleShutdown != NULL) {
- Py_DECREF(PyObject_CallFunction(__moduleShutdown, (char *)"()"));
- }
- // restore the "None-state"
+ // PYSIDE-585: It was crucial to update the refcounts *before*
+ // calling the shutdown.
Py_TYPE(qApp_content) = Py_NONE_TYPE;
Py_REFCNT(qApp_var) = qApp_var_ref;
- Py_REFCNT(qApp_content) = qApp_content_ref;
+ Py_REFCNT(qApp_content) = Py_REFCNT(Py_None);
+ if (__moduleShutdown != NULL)
+ Py_DECREF(PyObject_CallFunction(__moduleShutdown, (char *)"()"));
}
else
(void)PyObject_INIT(qApp_content, type);
@@ -160,7 +168,7 @@ setup_qApp_var(PyObject *module)
return -1;
// This is a borrowed reference
qApp_moduledicts[0] = PyEval_GetBuiltins();
- Py_INCREF(qApp_content);
+ Py_INCREF(qApp_moduledicts[0]);
init_done = 1;
}
@@ -170,7 +178,7 @@ setup_qApp_var(PyObject *module)
if (module_index) {
// This line gets a borrowed reference
qApp_moduledicts[module_index] = PyModule_GetDict(module);
- Py_INCREF(qApp_content);
+ Py_INCREF(qApp_moduledicts[module_index]);
if (reset_qApp_var() < 0)
return -1;
}