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DinoVdiegorusso
DinoV
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diegorusso
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pythongh-112075: Accessing a single element should optimistically avoid locking (python#115109)
Makes accessing a single element thread safe and typically lock free
1 parent 97f461b commit beeaa4a

3 files changed

Lines changed: 496 additions & 175 deletions

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‎Include/internal/pycore_dict.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -211,6 +211,8 @@ static inline PyDictUnicodeEntry* DK_UNICODE_ENTRIES(PyDictKeysObject *dk) {
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#define DICT_WATCHER_MASK ((1 << DICT_MAX_WATCHERS) - 1)
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#define DICT_WATCHER_AND_MODIFICATION_MASK ((1 << (DICT_MAX_WATCHERS + DICT_WATCHED_MUTATION_BITS)) - 1)
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#define DICT_VALUES_SIZE(values) ((uint8_t *)values)[-1]
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#ifdef Py_GIL_DISABLED
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#define DICT_NEXT_VERSION(INTERP) \
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(_Py_atomic_add_uint64(&(INTERP)->dict_state.global_version, DICT_VERSION_INCREMENT) + DICT_VERSION_INCREMENT)
@@ -256,7 +258,7 @@ _PyDictValues_AddToInsertionOrder(PyDictValues *values, Py_ssize_t ix)
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assert(ix < SHARED_KEYS_MAX_SIZE);
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uint8_t *size_ptr = ((uint8_t *)values)-2;
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int size = *size_ptr;
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assert(size+2 < ((uint8_t *)values)[-1]);
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assert(size+2 < DICT_VALUES_SIZE(values));
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size++;
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size_ptr[-size] = (uint8_t)ix;
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*size_ptr = size;

‎Objects/clinic/dictobject.c.h‎

Lines changed: 1 addition & 16 deletions
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