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 Does it 22 XXX mean that pointers previously obtained via PyArena_Malloc() are 23 XXX no longer valid?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
