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 Does it 25 XXX mean that pointers previously obtained via _PyArena_Malloc() are 26 XXX no longer valid?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