| |
| #ifndef Py_OBJIMPL_H |
| #define Py_OBJIMPL_H |
| |
| #include "pymem.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /* |
| Functions and macros for modules that implement new object types. |
| You must first include "object.h". |
| |
| - PyObject_New(type, typeobj) allocates memory for a new object of |
| the given type; here 'type' must be the C structure type used to |
| represent the object and 'typeobj' the address of the corresponding |
| type object. Reference count and type pointer are filled in; the |
| rest of the bytes of the object are *undefined*! The resulting |
| expression type is 'type *'. The size of the object is actually |
| determined by the tp_basicsize field of the type object. |
| |
| - PyObject_NewVar(type, typeobj, n) is similar but allocates a |
| variable-size object with n extra items. The size is computed as |
| tp_basicsize plus n * tp_itemsize. This fills in the ob_size field |
| as well. |
| |
| - PyObject_Del(op) releases the memory allocated for an object. |
| |
| - PyObject_Init(op, typeobj) and PyObject_InitVar(op, typeobj, n) are |
| similar to PyObject_{New, NewVar} except that they don't allocate |
| the memory needed for an object. Instead of the 'type' parameter, |
| they accept the pointer of a new object (allocated by an arbitrary |
| allocator) and initialize its object header fields. |
| |
| Note that objects created with PyObject_{New, NewVar} are allocated |
| within the Python heap by the raw memory allocator (usually the system |
| malloc). If you want to use the specialized Python allocator use |
| PyMalloc_New and PyMalloc_NewVar to allocate the objects and |
| PyMalloc_Del to free them. |
| |
| In case a specific form of memory management is needed, implying that |
| the objects would not reside in the Python heap (for example standard |
| malloc heap(s) are mandatory, use of shared memory, C++ local storage |
| or operator new), you must first allocate the object with your custom |
| allocator, then pass its pointer to PyObject_{Init, InitVar} for |
| filling in its Python-specific fields: reference count, type pointer, |
| possibly others. You should be aware that Python has very limited |
| control over these objects because they don't cooperate with the |
| Python memory manager. Such objects may not be eligible for automatic |
| garbage collection and you have to make sure that they are released |
| accordingly whenever their destructor gets called (cf. the specific |
| form of memory management you're using). |
| |
| Unless you have specific memory management requirements, it is |
| recommended to use PyObject_{New, NewVar, Del}. */ |
| |
| /* |
| * Raw object memory interface |
| * =========================== |
| */ |
| |
| /* The use of this API should be avoided, unless a builtin object |
| constructor inlines PyObject_{New, NewVar}, either because the |
| latter functions cannot allocate the exact amount of needed memory, |
| either for speed. This situation is exceptional, but occurs for |
| some object constructors (PyBuffer_New, PyList_New...). Inlining |
| PyObject_{New, NewVar} for objects that are supposed to belong to |
| the Python heap is discouraged. If you really have to, make sure |
| the object is initialized with PyObject_{Init, InitVar}. Do *not* |
| inline PyObject_{Init, InitVar} for user-extension types or you |
| might seriously interfere with Python's memory management. */ |
| |
| /* Functions */ |
| |
| /* Wrappers that useful if you need to be sure that you are using the |
| same object memory allocator as Python. These wrappers *do not* make |
| sure that allocating 0 bytes returns a non-NULL pointer. Returned |
| pointers must be checked for NULL explicitly; no action is performed |
| on failure. */ |
| extern DL_IMPORT(void *) PyObject_Malloc(size_t); |
| extern DL_IMPORT(void *) PyObject_Realloc(void *, size_t); |
| extern DL_IMPORT(void) PyObject_Free(void *); |
| |
| /* Macros */ |
| #define PyObject_MALLOC(n) PyMem_MALLOC(n) |
| #define PyObject_REALLOC(op, n) PyMem_REALLOC((void *)(op), (n)) |
| #define PyObject_FREE(op) PyMem_FREE((void *)(op)) |
| |
| /* |
| * Generic object allocator interface |
| * ================================== |
| */ |
| |
| /* Functions */ |
| extern DL_IMPORT(PyObject *) PyObject_Init(PyObject *, PyTypeObject *); |
| extern DL_IMPORT(PyVarObject *) PyObject_InitVar(PyVarObject *, |
| PyTypeObject *, int); |
| extern DL_IMPORT(PyObject *) _PyObject_New(PyTypeObject *); |
| extern DL_IMPORT(PyVarObject *) _PyObject_NewVar(PyTypeObject *, int); |
| extern DL_IMPORT(void) _PyObject_Del(PyObject *); |
| |
| #define PyObject_New(type, typeobj) \ |
| ( (type *) _PyObject_New(typeobj) ) |
| #define PyObject_NewVar(type, typeobj, n) \ |
| ( (type *) _PyObject_NewVar((typeobj), (n)) ) |
| #define PyObject_Del(op) _PyObject_Del((PyObject *)(op)) |
| |
| /* Macros trading binary compatibility for speed. See also pymem.h. |
| Note that these macros expect non-NULL object pointers.*/ |
| #define PyObject_INIT(op, typeobj) \ |
| ( (op)->ob_type = (typeobj), _Py_NewReference((PyObject *)(op)), (op) ) |
| #define PyObject_INIT_VAR(op, typeobj, size) \ |
| ( (op)->ob_size = (size), PyObject_INIT((op), (typeobj)) ) |
| |
| #define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize ) |
| |
| /* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a |
| vrbl-size object with nitems items, exclusive of gc overhead (if any). The |
| value is rounded up to the closest multiple of sizeof(void *), in order to |
| ensure that pointer fields at the end of the object are correctly aligned |
| for the platform (this is of special importance for subclasses of, e.g., |
| str or long, so that pointers can be stored after the embedded data). |
| |
| Note that there's no memory wastage in doing this, as malloc has to |
| return (at worst) pointer-aligned memory anyway. |
| */ |
| #if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0 |
| # error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2" |
| #endif |
| |
| #define _PyObject_VAR_SIZE(typeobj, nitems) \ |
| (size_t) \ |
| ( ( (typeobj)->tp_basicsize + \ |
| (nitems)*(typeobj)->tp_itemsize + \ |
| (SIZEOF_VOID_P - 1) \ |
| ) & ~(SIZEOF_VOID_P - 1) \ |
| ) |
| |
| #define PyObject_NEW(type, typeobj) \ |
| ( (type *) PyObject_Init( \ |
| (PyObject *) PyObject_MALLOC( _PyObject_SIZE(typeobj) ), (typeobj)) ) |
| |
| #define PyObject_NEW_VAR(type, typeobj, n) \ |
| ( (type *) PyObject_InitVar( \ |
| (PyVarObject *) PyObject_MALLOC(_PyObject_VAR_SIZE((typeobj),(n)) ),\ |
| (typeobj), (n)) ) |
| |
| #define PyObject_DEL(op) PyObject_FREE(op) |
| |
| /* This example code implements an object constructor with a custom |
| allocator, where PyObject_New is inlined, and shows the important |
| distinction between two steps (at least): |
| 1) the actual allocation of the object storage; |
| 2) the initialization of the Python specific fields |
| in this storage with PyObject_{Init, InitVar}. |
| |
| PyObject * |
| YourObject_New(...) |
| { |
| PyObject *op; |
| |
| op = (PyObject *) Your_Allocator(_PyObject_SIZE(YourTypeStruct)); |
| if (op == NULL) |
| return PyErr_NoMemory(); |
| |
| op = PyObject_Init(op, &YourTypeStruct); |
| if (op == NULL) |
| return NULL; |
| |
| op->ob_field = value; |
| ... |
| return op; |
| } |
| |
| Note that in C++, the use of the new operator usually implies that |
| the 1st step is performed automatically for you, so in a C++ class |
| constructor you would start directly with PyObject_Init/InitVar. */ |
| |
| /* |
| * The PyMalloc Object Allocator |
| * ============================= |
| */ |
| |
| extern DL_IMPORT(PyObject *) _PyMalloc_New(PyTypeObject *); |
| extern DL_IMPORT(PyVarObject *) _PyMalloc_NewVar(PyTypeObject *, int); |
| extern DL_IMPORT(void) _PyMalloc_Del(PyObject *); |
| |
| #define PyMalloc_New(type, typeobj) \ |
| ( (type *) _PyMalloc_New(typeobj) ) |
| #define PyMalloc_NewVar(type, typeobj, n) \ |
| ( (type *) _PyMalloc_NewVar((typeobj), (n)) ) |
| #define PyMalloc_Del(op) _PyMalloc_Del((PyObject *)(op)) |
| |
| |
| /* |
| * Garbage Collection Support |
| * ========================== |
| * |
| * Some of the functions and macros below are always defined; when |
| * WITH_CYCLE_GC is undefined, they simply don't do anything different |
| * than their non-GC counterparts. |
| */ |
| |
| /* Test if a type has a GC head */ |
| #define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC) |
| |
| /* Test if an object has a GC head */ |
| #define PyObject_IS_GC(o) (PyType_IS_GC((o)->ob_type) && \ |
| ((o)->ob_type->tp_is_gc == NULL || (o)->ob_type->tp_is_gc(o))) |
| |
| extern DL_IMPORT(PyObject *) _PyObject_GC_Malloc(PyTypeObject *, int); |
| extern DL_IMPORT(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, int); |
| |
| #define PyObject_GC_Resize(type, op, n) \ |
| ( (type *) _PyObject_GC_Resize((PyVarObject *)(op), (n)) ) |
| |
| extern DL_IMPORT(PyObject *) _PyObject_GC_New(PyTypeObject *); |
| extern DL_IMPORT(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, int); |
| extern DL_IMPORT(void) _PyObject_GC_Del(PyObject *); |
| extern DL_IMPORT(void) _PyObject_GC_Track(PyObject *); |
| extern DL_IMPORT(void) _PyObject_GC_UnTrack(PyObject *); |
| |
| #ifdef WITH_CYCLE_GC |
| |
| /* GC information is stored BEFORE the object structure */ |
| typedef union _gc_head { |
| struct { |
| union _gc_head *gc_next; /* not NULL if object is tracked */ |
| union _gc_head *gc_prev; |
| int gc_refs; |
| } gc; |
| long double dummy; /* force worst-case alignment */ |
| } PyGC_Head; |
| |
| extern PyGC_Head _PyGC_generation0; |
| |
| /* Tell the GC to track this object. NB: While the object is tracked the |
| * collector it must be safe to call the ob_traverse method. */ |
| #define _PyObject_GC_TRACK(o) do { \ |
| PyGC_Head *g = (PyGC_Head *)(o)-1; \ |
| if (g->gc.gc_next != NULL) \ |
| Py_FatalError("GC object already in linked list"); \ |
| g->gc.gc_next = &_PyGC_generation0; \ |
| g->gc.gc_prev = _PyGC_generation0.gc.gc_prev; \ |
| g->gc.gc_prev->gc.gc_next = g; \ |
| _PyGC_generation0.gc.gc_prev = g; \ |
| } while (0); |
| |
| /* Tell the GC to stop tracking this object. */ |
| #define _PyObject_GC_UNTRACK(o) do { \ |
| PyGC_Head *g = (PyGC_Head *)(o)-1; \ |
| g->gc.gc_prev->gc.gc_next = g->gc.gc_next; \ |
| g->gc.gc_next->gc.gc_prev = g->gc.gc_prev; \ |
| g->gc.gc_next = NULL; \ |
| } while (0); |
| |
| #define PyObject_GC_Track(op) _PyObject_GC_Track((PyObject *)op) |
| #define PyObject_GC_UnTrack(op) _PyObject_GC_UnTrack((PyObject *)op) |
| |
| |
| #define PyObject_GC_New(type, typeobj) \ |
| ( (type *) _PyObject_GC_New(typeobj) ) |
| #define PyObject_GC_NewVar(type, typeobj, n) \ |
| ( (type *) _PyObject_GC_NewVar((typeobj), (n)) ) |
| #define PyObject_GC_Del(op) _PyObject_GC_Del((PyObject *)(op)) |
| |
| #else /* !WITH_CYCLE_GC */ |
| |
| #define PyObject_GC_New PyObject_New |
| #define PyObject_GC_NewVar PyObject_NewVar |
| #define PyObject_GC_Del PyObject_Del |
| #define _PyObject_GC_TRACK(op) |
| #define _PyObject_GC_UNTRACK(op) |
| #define PyObject_GC_Track(op) |
| #define PyObject_GC_UnTrack(op) |
| |
| #endif |
| |
| /* This is here for the sake of backwards compatibility. Extensions that |
| * use the old GC API will still compile but the objects will not be |
| * tracked by the GC. */ |
| #define PyGC_HEAD_SIZE 0 |
| #define PyObject_GC_Init(op) |
| #define PyObject_GC_Fini(op) |
| #define PyObject_AS_GC(op) (op) |
| #define PyObject_FROM_GC(op) (op) |
| |
| |
| /* Test if a type supports weak references */ |
| #define PyType_SUPPORTS_WEAKREFS(t) \ |
| (PyType_HasFeature((t), Py_TPFLAGS_HAVE_WEAKREFS) \ |
| && ((t)->tp_weaklistoffset > 0)) |
| |
| #define PyObject_GET_WEAKREFS_LISTPTR(o) \ |
| ((PyObject **) (((char *) (o)) + (o)->ob_type->tp_weaklistoffset)) |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| #endif /* !Py_OBJIMPL_H */ |