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23 | XXX no longer valid?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