#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 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. It does not run a destructor -- it only frees the memory. PyObject_Free is identical. - 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 using the specialized Python allocator (implemented in obmalloc.c), if WITH_PYMALLOC is enabled. In addition, a special debugging allocator is used if PYMALLOC_DEBUG is also #defined. 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 */ /* Functions to call the same malloc/realloc/free as used by Python's object allocator. If WITH_PYMALLOC is enabled, these may differ from the platform malloc/realloc/free. The Python object allocator is designed for fast, cache-conscious allocation of many "small" objects, with low hidden memory overhead. PyObject_Malloc(0) returns a unique non-NULL pointer if possible. PyObject_Realloc(NULL, n) acts like PyObject_Malloc(n). PyObject_Realloc(p != NULL, 0) does not return NULL or free the memory at p. Returned pointers must be checked for NULL explicitly; no action is performed on failure other than to return NULL. */ 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 */ #ifdef WITH_PYMALLOC #ifdef PYMALLOC_DEBUG DL_IMPORT(void *) _PyObject_DebugMalloc(size_t nbytes); DL_IMPORT(void *) _PyObject_DebugRealloc(void *p, size_t nbytes); DL_IMPORT(void) _PyObject_DebugFree(void *p); DL_IMPORT(void) _PyObject_DebugDumpAddress(const void *p); DL_IMPORT(void) _PyObject_DebugCheckAddress(const void *p); DL_IMPORT(void) _PyObject_DebugDumpStats(void); #define PyObject_MALLOC _PyObject_DebugMalloc #define PyObject_Malloc _PyObject_DebugMalloc #define PyObject_REALLOC _PyObject_DebugRealloc #define PyObject_Realloc _PyObject_DebugRealloc #define PyObject_FREE _PyObject_DebugFree #define PyObject_Free _PyObject_DebugFree #else /* WITH_PYMALLOC && ! PYMALLOC_DEBUG */ #define PyObject_MALLOC PyObject_Malloc #define PyObject_REALLOC PyObject_Realloc #define PyObject_FREE PyObject_Free #endif #else /* ! WITH_PYMALLOC */ #define PyObject_MALLOC PyMem_MALLOC #define PyObject_REALLOC PyMem_REALLOC #define PyObject_FREE PyMem_FREE #endif /* WITH_PYMALLOC */ #define PyObject_Del PyObject_Free #define PyObject_DEL PyObject_FREE /* for source compatibility with 2.2 */ #define _PyObject_Del PyObject_Free /* * 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); #define PyObject_New(type, typeobj) \ ( (type *) _PyObject_New(typeobj) ) #define PyObject_NewVar(type, typeobj, n) \ ( (type *) _PyObject_NewVar((typeobj), (n)) ) /* 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)) ) /* 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. */ /* * 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(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, int); #define PyObject_GC_Resize(type, op, n) \ ( (type *) _PyObject_GC_Resize((PyVarObject *)(op), (n)) ) /* for source compatibility with 2.2 */ #define _PyObject_GC_Del PyObject_GC_Del #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; #define _Py_AS_GC(o) ((PyGC_Head *)(o)-1) /* 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 = _Py_AS_GC(o); \ 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 = _Py_AS_GC(o); \ 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); extern DL_IMPORT(PyObject *) _PyObject_GC_Malloc(size_t); extern DL_IMPORT(PyObject *) _PyObject_GC_New(PyTypeObject *); extern DL_IMPORT(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, int); extern DL_IMPORT(void) PyObject_GC_Track(void *); extern DL_IMPORT(void) PyObject_GC_UnTrack(void *); extern DL_IMPORT(void) PyObject_GC_Del(void *); #define PyObject_GC_New(type, typeobj) \ ( (type *) _PyObject_GC_New(typeobj) ) #define PyObject_GC_NewVar(type, typeobj, n) \ ( (type *) _PyObject_GC_NewVar((typeobj), (n)) ) #else /* !WITH_CYCLE_GC */ #define _PyObject_GC_Malloc PyObject_Malloc #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 */