bpo-40241: Add pycore_gc.h header file (GH-19494) · python/cpython@0135598 (original) (raw)

`@@ -125,61 +125,12 @@ PyAPI_FUNC(Py_ssize_t) _PyGC_CollectIfEnabled(void);

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` (PyType_IS_GC(Py_TYPE(o)) \

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` && (Py_TYPE(o)->tp_is_gc == NULL || Py_TYPE(o)->tp_is_gc(o)))

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/* GC information is stored BEFORE the object structure. */

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typedef struct {

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// Pointer to next object in the list.

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// 0 means the object is not tracked

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uintptr_t _gc_next;

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-

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// Pointer to previous object in the list.

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// Lowest two bits are used for flags documented later.

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uintptr_t _gc_prev;

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} PyGC_Head;

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-

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#define _Py_AS_GC(o) ((PyGC_Head *)(o)-1)

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-

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/* True if the object is currently tracked by the GC. */

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#define _PyObject_GC_IS_TRACKED(o) (_Py_AS_GC(o)->_gc_next != 0)

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-

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/* True if the object may be tracked by the GC in the future, or already is.

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This can be useful to implement some optimizations. */

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#define _PyObject_GC_MAY_BE_TRACKED(obj) \

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(PyObject_IS_GC(obj) && \

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(!PyTuple_CheckExact(obj) || _PyObject_GC_IS_TRACKED(obj)))

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-

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-

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/* Bit flags for _gc_prev */

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/* Bit 0 is set when tp_finalize is called */

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#define _PyGC_PREV_MASK_FINALIZED (1)

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/* Bit 1 is set when the object is in generation which is GCed currently. */

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#define _PyGC_PREV_MASK_COLLECTING (2)

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/* The (N-2) most significant bits contain the real address. */

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#define _PyGC_PREV_SHIFT (2)

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#define _PyGC_PREV_MASK (((uintptr_t) -1) << _PyGC_PREV_SHIFT)

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-

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// Lowest bit of _gc_next is used for flags only in GC.

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// But it is always 0 for normal code.

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#define _PyGCHead_NEXT(g) ((PyGC_Head*)(g)->_gc_next)

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#define _PyGCHead_SET_NEXT(g, p) ((g)->_gc_next = (uintptr_t)(p))

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-

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// Lowest two bits of _gc_prev is used for PyGC_PREV_MASK* flags.

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#define _PyGCHead_PREV(g) ((PyGC_Head*)((g)->_gc_prev & _PyGC_PREV_MASK))

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#define _PyGCHead_SET_PREV(g, p) do { \

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assert(((uintptr_t)p & ~_PyGC_PREV_MASK) == 0); \

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(g)->_gc_prev = ((g)->_gc_prev & ~_PyGC_PREV_MASK) \

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| ((uintptr_t)(p)); \

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} while (0)

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-

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#define _PyGCHead_FINALIZED(g) \

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(((g)->_gc_prev & _PyGC_PREV_MASK_FINALIZED) != 0)

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#define _PyGCHead_SET_FINALIZED(g) \

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((g)->_gc_prev |= _PyGC_PREV_MASK_FINALIZED)

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-

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#define _PyGC_FINALIZED(o) \

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_PyGCHead_FINALIZED(_Py_AS_GC(o))

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#define _PyGC_SET_FINALIZED(o) \

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_PyGCHead_SET_FINALIZED(_Py_AS_GC(o))

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-

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/* Code built with Py_BUILD_CORE must include pycore_gc.h instead which

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defines a different _PyGC_FINALIZED() macro. */

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#ifndef Py_BUILD_CORE

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// Kept for backward compatibility with Python 3.8

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define _PyGC_FINALIZED(o) PyObject_GC_IsFinalized(o)

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#endif

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`PyAPI_FUNC(PyObject *) _PyObject_GC_Malloc(size_t size);

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`PyAPI_FUNC(PyObject *) _PyObject_GC_Calloc(size_t size);