Thread safe lock-free iteration

Author: DinoV

Include/internal/pycore_dict.h

@@ -205,6 +205,8 @@ static inline PyDictUnicodeEntry* DK_UNICODE_ENTRIES(PyDictKeysObject *dk) {
 #define DICT_WATCHER_MASK ((1 << DICT_MAX_WATCHERS) - 1)
 #define DICT_WATCHER_AND_MODIFICATION_MASK ((1 << (DICT_MAX_WATCHERS + DICT_WATCHED_MUTATION_BITS)) - 1)
 
+#define DICT_VALUES_USED_SIZE(values) ((uint8_t *)values)[-2]
+
 #ifdef Py_GIL_DISABLED
 #define DICT_NEXT_VERSION(INTERP) \
     (_Py_atomic_add_uint64(&(INTERP)->dict_state.global_version, DICT_VERSION_INCREMENT) + DICT_VERSION_INCREMENT)