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 |
7 | extern "C" { |
8 | #endif |
9 | |
10 | #ifndef Py_BUILD_CORE |
11 | # error "this header requires Py_BUILD_CORE define" |
12 | #endif |
13 | |
14 | typedef 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26 | XXX no longer valid?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 | */ |
38 | PyAPI_FUNC(PyArena*) _PyArena_New(void); |
39 | PyAPI_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 | */ |
53 | PyAPI_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 | */ |
59 | PyAPI_FUNC(int) _PyArena_AddPyObject(PyArena *, PyObject *); |
60 | |
61 | #ifdef __cplusplus |
62 | } |
63 | #endif |
64 | #endif /* !Py_INTERNAL_PYARENA_H */ |
65 | |