1/* An arena-like memory interface for the compiler.
2 */
3
4#ifndef Py_INTERNAL_PYARENA_H
5#define Py_INTERNAL_PYARENA_H
6#ifdef __cplusplus
7extern "C" {
8#endif
9
10#ifndef Py_BUILD_CORE
11# error "this header requires Py_BUILD_CORE define"
12#endif
13
14typedef struct _arena PyArena;
15
16/* _PyArena_New() and _PyArena_Free() create a new arena and free it,
17 respectively. Once an arena has been created, it can be used
18 to allocate memory via _PyArena_Malloc(). Pointers to PyObject can
19 also be registered with the arena via _PyArena_AddPyObject(), and the
20 arena will ensure that the PyObjects stay alive at least until
21 _PyArena_Free() is called. When an arena is freed, all the memory it
22 allocated is freed, the arena releases internal references to registered
23 PyObject*, and none of its pointers are valid.
24 XXX (tim) What does "none of its pointers are valid" mean? Does it
25 XXX mean that pointers previously obtained via _PyArena_Malloc() are
26 XXX no longer valid? (That's clearly true, but not sure that's what
27 XXX the text is trying to say.)
28
29 _PyArena_New() returns an arena pointer. On error, it
30 returns a negative number and sets an exception.
31 XXX (tim): Not true. On error, _PyArena_New() actually returns NULL,
32 XXX and looks like it may or may not set an exception (e.g., if the
33 XXX internal PyList_New(0) returns NULL, _PyArena_New() passes that on
34 XXX and an exception is set; OTOH, if the internal
35 XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but
36 XXX an exception is not set in that case).
37*/
38PyAPI_FUNC(PyArena*) _PyArena_New(void);
39PyAPI_FUNC(void) _PyArena_Free(PyArena *);
40
41/* Mostly like malloc(), return the address of a block of memory spanning
42 * `size` bytes, or return NULL (without setting an exception) if enough
43 * new memory can't be obtained. Unlike malloc(0), _PyArena_Malloc() with
44 * size=0 does not guarantee to return a unique pointer (the pointer
45 * returned may equal one or more other pointers obtained from
46 * _PyArena_Malloc()).
47 * Note that pointers obtained via _PyArena_Malloc() must never be passed to
48 * the system free() or realloc(), or to any of Python's similar memory-
49 * management functions. _PyArena_Malloc()-obtained pointers remain valid
50 * until _PyArena_Free(ar) is called, at which point all pointers obtained
51 * from the arena `ar` become invalid simultaneously.
52 */
53PyAPI_FUNC(void*) _PyArena_Malloc(PyArena *, size_t size);
54
55/* This routine isn't a proper arena allocation routine. It takes
56 * a PyObject* and records it so that it can be DECREFed when the
57 * arena is freed.
58 */
59PyAPI_FUNC(int) _PyArena_AddPyObject(PyArena *, PyObject *);
60
61#ifdef __cplusplus
62}
63#endif
64#endif /* !Py_INTERNAL_PYARENA_H */
65