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 Does it 23 XXX mean that pointers previously obtained via PyArena_Malloc() are 24 XXX no longer valid?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