Issue #18112: PEP 442 implementation (safe object finalization).
diff --git a/Include/object.h b/Include/object.h
index 221b4a2..25b96e8 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -408,6 +408,8 @@
/* Type attribute cache version tag. Added in version 2.6 */
unsigned int tp_version_tag;
+ destructor tp_finalize;
+
#ifdef COUNT_ALLOCS
/* these must be last and never explicitly initialized */
Py_ssize_t tp_allocs;
@@ -529,6 +531,8 @@
PyAPI_FUNC(int) PyCallable_Check(PyObject *);
PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
+PyAPI_FUNC(void) PyObject_CallFinalizer(PyObject *);
+PyAPI_FUNC(int) PyObject_CallFinalizerFromDealloc(PyObject *);
/* Same as PyObject_Generic{Get,Set}Attr, but passing the attributes
dict as the last parameter. */
@@ -646,6 +650,12 @@
Py_TPFLAGS_HAVE_VERSION_TAG | \
0)
+/* NOTE: The following flags reuse lower bits (removed as part of the
+ * Python 3.0 transition). */
+
+/* Type structure has tp_finalize member (3.4) */
+#define Py_TPFLAGS_HAVE_FINALIZE (1UL << 0)
+
#ifdef Py_LIMITED_API
#define PyType_HasFeature(t,f) ((PyType_GetFlags(t) & (f)) != 0)
#else
diff --git a/Include/objimpl.h b/Include/objimpl.h
index 4e72a46..264c120 100644
--- a/Include/objimpl.h
+++ b/Include/objimpl.h
@@ -256,6 +256,30 @@
#define _Py_AS_GC(o) ((PyGC_Head *)(o)-1)
+/* Bit 0 is set when tp_finalize is called */
+#define _PyGC_REFS_MASK_FINALIZED (1 << 0)
+/* The (N-1) most significant bits contain the gc state / refcount */
+#define _PyGC_REFS_SHIFT (1)
+#define _PyGC_REFS_MASK (((size_t) -1) << _PyGC_REFS_SHIFT)
+
+#define _PyGCHead_REFS(g) ((g)->gc.gc_refs >> _PyGC_REFS_SHIFT)
+#define _PyGCHead_SET_REFS(g, v) do { \
+ (g)->gc.gc_refs = ((g)->gc.gc_refs & ~_PyGC_REFS_MASK) \
+ | (v << _PyGC_REFS_SHIFT); \
+ } while (0)
+#define _PyGCHead_DECREF(g) ((g)->gc.gc_refs -= 1 << _PyGC_REFS_SHIFT)
+
+#define _PyGCHead_FINALIZED(g) (((g)->gc.gc_refs & _PyGC_REFS_MASK_FINALIZED) != 0)
+#define _PyGCHead_SET_FINALIZED(g, v) do { \
+ (g)->gc.gc_refs = ((g)->gc.gc_refs & ~_PyGC_REFS_MASK_FINALIZED) \
+ | (v != 0); \
+ } while (0)
+
+#define _PyGC_FINALIZED(o) _PyGCHead_FINALIZED(_Py_AS_GC(o))
+#define _PyGC_SET_FINALIZED(o, v) _PyGCHead_SET_FINALIZED(_Py_AS_GC(o), v)
+
+#define _PyGC_REFS(o) _PyGCHead_REFS(_Py_AS_GC(o))
+
#define _PyGC_REFS_UNTRACKED (-2)
#define _PyGC_REFS_REACHABLE (-3)
#define _PyGC_REFS_TENTATIVELY_UNREACHABLE (-4)
@@ -264,9 +288,9 @@
* collector it must be safe to call the ob_traverse method. */
#define _PyObject_GC_TRACK(o) do { \
PyGC_Head *g = _Py_AS_GC(o); \
- if (g->gc.gc_refs != _PyGC_REFS_UNTRACKED) \
+ if (_PyGCHead_REFS(g) != _PyGC_REFS_UNTRACKED) \
Py_FatalError("GC object already tracked"); \
- g->gc.gc_refs = _PyGC_REFS_REACHABLE; \
+ _PyGCHead_SET_REFS(g, _PyGC_REFS_REACHABLE); \
g->gc.gc_next = _PyGC_generation0; \
g->gc.gc_prev = _PyGC_generation0->gc.gc_prev; \
g->gc.gc_prev->gc.gc_next = g; \
@@ -279,8 +303,8 @@
*/
#define _PyObject_GC_UNTRACK(o) do { \
PyGC_Head *g = _Py_AS_GC(o); \
- assert(g->gc.gc_refs != _PyGC_REFS_UNTRACKED); \
- g->gc.gc_refs = _PyGC_REFS_UNTRACKED; \
+ assert(_PyGCHead_REFS(g) != _PyGC_REFS_UNTRACKED); \
+ _PyGCHead_SET_REFS(g, _PyGC_REFS_UNTRACKED); \
g->gc.gc_prev->gc.gc_next = g->gc.gc_next; \
g->gc.gc_next->gc.gc_prev = g->gc.gc_prev; \
g->gc.gc_next = NULL; \
@@ -288,7 +312,7 @@
/* True if the object is currently tracked by the GC. */
#define _PyObject_GC_IS_TRACKED(o) \
- ((_Py_AS_GC(o))->gc.gc_refs != _PyGC_REFS_UNTRACKED)
+ (_PyGC_REFS(o) != _PyGC_REFS_UNTRACKED)
/* True if the object may be tracked by the GC in the future, or already is.
This can be useful to implement some optimizations. */