bpo-1635741: Fix unicode_dealloc() for mortal interned string (GH-21270)

When unicode_dealloc() is called on a mortal interned string, the
string reference counter is now reset at zero.
This commit is contained in:
Victor Stinner 2020-07-03 16:59:12 +02:00 committed by GitHub
parent 91e1bc18bd
commit 3549ca313a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 4 deletions

View File

@ -1943,13 +1943,20 @@ unicode_dealloc(PyObject *unicode)
break;
case SSTATE_INTERNED_MORTAL:
/* revive dead object temporarily for DelItem */
Py_SET_REFCNT(unicode, 3);
#ifdef INTERNED_STRINGS
/* Revive the dead object temporarily. PyDict_DelItem() removes two
references (key and value) which were ignored by
PyUnicode_InternInPlace(). Use refcnt=3 rather than refcnt=2
to prevent calling unicode_dealloc() again. Adjust refcnt after
PyDict_DelItem(). */
assert(Py_REFCNT(unicode) == 0);
Py_SET_REFCNT(unicode, 3);
if (PyDict_DelItem(interned, unicode) != 0) {
_PyErr_WriteUnraisableMsg("deletion of interned string failed",
NULL);
}
assert(Py_REFCNT(unicode) == 1);
Py_SET_REFCNT(unicode, 0);
#endif
break;
@ -15710,8 +15717,9 @@ PyUnicode_InternInPlace(PyObject **p)
return;
}
/* The two references in interned are not counted by refcnt.
The deallocator will take care of this */
/* The two references in interned dict (key and value) are not counted by
refcnt. unicode_dealloc() and _PyUnicode_ClearInterned() take care of
this. */
Py_SET_REFCNT(s, Py_REFCNT(s) - 2);
_PyUnicode_STATE(s).interned = SSTATE_INTERNED_MORTAL;
#endif
@ -15780,6 +15788,8 @@ _PyUnicode_ClearInterned(PyThreadState *tstate)
#endif
break;
case SSTATE_INTERNED_MORTAL:
// Restore the two references (key and value) ignored
// by PyUnicode_InternInPlace().
Py_SET_REFCNT(s, Py_REFCNT(s) + 2);
#ifdef INTERNED_STATS
mortal_size += PyUnicode_GET_LENGTH(s);