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1: /* The PyObject_ memory family: high-level object memory interfaces. 2: See pymem.h for the low-level PyMem_ family. 3: */ 4: 5: #ifndef Py_OBJIMPL_H 6: #define Py_OBJIMPL_H 7: 8: #include "pymem.h" 9: 10: #ifdef __cplusplus 11: extern "C" { 12: #endif 13: 14: /* BEWARE: 15: 16: Each interface exports both functions and macros. Extension modules should 17: use the functions, to ensure binary compatibility across Python versions. 18: Because the Python implementation is free to change internal details, and 19: the macros may (or may not) expose details for speed, if you do use the 20: macros you must recompile your extensions with each Python release. 21: 22: Never mix calls to PyObject_ memory functions with calls to the platform 23: malloc/realloc/ calloc/free, or with calls to PyMem_. 24: */ 25: 26: /* 27: Functions and macros for modules that implement new object types. 28: 29: - PyObject_New(type, typeobj) allocates memory for a new object of the given 30: type, and initializes part of it. 'type' must be the C structure type used 31: to represent the object, and 'typeobj' the address of the corresponding 32: type object. Reference count and type pointer are filled in; the rest of 33: the bytes of the object are *undefined*! The resulting expression type is 34: 'type *'. The size of the object is determined by the tp_basicsize field 35: of the type object. 36: 37: - PyObject_NewVar(type, typeobj, n) is similar but allocates a variable-size 38: object with room for n items. In addition to the refcount and type pointer 39: fields, this also fills in the ob_size field. 40: 41: - PyObject_Del(op) releases the memory allocated for an object. It does not 42: run a destructor -- it only frees the memory. PyObject_Free is identical. 43: 44: - PyObject_Init(op, typeobj) and PyObject_InitVar(op, typeobj, n) don't 45: allocate memory. Instead of a 'type' parameter, they take a pointer to a 46: new object (allocated by an arbitrary allocator), and initialize its object 47: header fields. 48: 49: Note that objects created with PyObject_{New, NewVar} are allocated using the 50: specialized Python allocator (implemented in obmalloc.c), if WITH_PYMALLOC is 51: enabled. In addition, a special debugging allocator is used if PYMALLOC_DEBUG 52: is also #defined. 53: 54: In case a specific form of memory management is needed (for example, if you 55: must use the platform malloc heap(s), or shared memory, or C++ local storage or 56: operator new), you must first allocate the object with your custom allocator, 57: then pass its pointer to PyObject_{Init, InitVar} for filling in its Python- 58: specific fields: reference count, type pointer, possibly others. You should 59: be aware that Python no control over these objects because they don't 60: cooperate with the Python memory manager. Such objects may not be eligible 61: for automatic garbage collection and you have to make sure that they are 62: released accordingly whenever their destructor gets called (cf. the specific 63: form of memory management you're using). 64: 65: Unless you have specific memory management requirements, use 66: PyObject_{New, NewVar, Del}. 67: */ 68: 69: /* 70: * Raw object memory interface 71: * =========================== 72: */ 73: 74: /* Functions to call the same malloc/realloc/free as used by Python's 75: object allocator. If WITH_PYMALLOC is enabled, these may differ from 76: the platform malloc/realloc/free. The Python object allocator is 77: designed for fast, cache-conscious allocation of many "small" objects, 78: and with low hidden memory overhead. 79: 80: PyObject_Malloc(0) returns a unique non-NULL pointer if possible. 81: 82: PyObject_Realloc(NULL, n) acts like PyObject_Malloc(n). 83: PyObject_Realloc(p != NULL, 0) does not return NULL, or free the memory 84: at p. 85: 86: Returned pointers must be checked for NULL explicitly; no action is 87: performed on failure other than to return NULL (no warning it printed, no 88: exception is set, etc). 89: 90: For allocating objects, use PyObject_{New, NewVar} instead whenever 91: possible. The PyObject_{Malloc, Realloc, Free} family is exposed 92: so that you can exploit Python's small-block allocator for non-object 93: uses. If you must use these routines to allocate object memory, make sure 94: the object gets initialized via PyObject_{Init, InitVar} after obtaining 95: the raw memory. 96: */ 97: PyAPI_FUNC(void *) PyObject_Malloc(size_t size); 98: #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03050000 99: PyAPI_FUNC(void *) PyObject_Calloc(size_t nelem, size_t elsize); 100: #endif 101: PyAPI_FUNC(void *) PyObject_Realloc(void *ptr, size_t new_size); 102: PyAPI_FUNC(void) PyObject_Free(void *ptr); 103: 104: #ifndef Py_LIMITED_API 105: /* This function returns the number of allocated memory blocks, regardless of size */ 106: PyAPI_FUNC(Py_ssize_t) _Py_GetAllocatedBlocks(void); 107: #endif /* !Py_LIMITED_API */ 108: 109: /* Macros */ 110: #ifdef WITH_PYMALLOC 111: #ifndef Py_LIMITED_API 112: PyAPI_FUNC(void) _PyObject_DebugMallocStats(FILE *out); 113: #endif /* #ifndef Py_LIMITED_API */ 114: #endif 115: 116: /* Macros */ 117: #define PyObject_MALLOC PyObject_Malloc 118: #define PyObject_REALLOC PyObject_Realloc 119: #define PyObject_FREE PyObject_Free 120: #define PyObject_Del PyObject_Free 121: #define PyObject_DEL PyObject_Free 122: 123: 124: /* 125: * Generic object allocator interface 126: * ================================== 127: */ 128: 129: /* Functions */ 130: PyAPI_FUNC(PyObject *) PyObject_Init(PyObject *, PyTypeObject *); 131: PyAPI_FUNC(PyVarObject *) PyObject_InitVar(PyVarObject *, 132: PyTypeObject *, Py_ssize_t); 133: PyAPI_FUNC(PyObject *) _PyObject_New(PyTypeObject *); 134: PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t); 135: 136: #define PyObject_New(type, typeobj) \ 137: ( (type *) _PyObject_New(typeobj) ) 138: #define PyObject_NewVar(type, typeobj, n) \ 139: ( (type *) _PyObject_NewVar((typeobj), (n)) ) 140: 141: /* Macros trading binary compatibility for speed. See also pymem.h. 142: Note that these macros expect non-NULL object pointers.*/ 143: #define PyObject_INIT(op, typeobj) \ 144: ( Py_TYPE(op) = (typeobj), _Py_NewReference((PyObject *)(op)), (op) ) 145: #define PyObject_INIT_VAR(op, typeobj, size) \ 146: ( Py_SIZE(op) = (size), PyObject_INIT((op), (typeobj)) ) 147: 148: #define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize ) 149: 150: /* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a 151: vrbl-size object with nitems items, exclusive of gc overhead (if any). The 152: value is rounded up to the closest multiple of sizeof(void *), in order to 153: ensure that pointer fields at the end of the object are correctly aligned 154: for the platform (this is of special importance for subclasses of, e.g., 155: str or int, so that pointers can be stored after the embedded data). 156: 157: Note that there's no memory wastage in doing this, as malloc has to 158: return (at worst) pointer-aligned memory anyway. 159: */ 160: #if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0 161: # error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2" 162: #endif 163: 164: #define _PyObject_VAR_SIZE(typeobj, nitems) \ 165: _Py_SIZE_ROUND_UP((typeobj)->tp_basicsize + \ 166: (nitems)*(typeobj)->tp_itemsize, \ 167: SIZEOF_VOID_P) 168: 169: #define PyObject_NEW(type, typeobj) \ 170: ( (type *) PyObject_Init( \ 171: (PyObject *) PyObject_MALLOC( _PyObject_SIZE(typeobj) ), (typeobj)) ) 172: 173: #define PyObject_NEW_VAR(type, typeobj, n) \ 174: ( (type *) PyObject_InitVar( \ 175: (PyVarObject *) PyObject_MALLOC(_PyObject_VAR_SIZE((typeobj),(n)) ),\ (typeobj), (n)) ) 177: 178: /* This example code implements an object constructor with a custom 179: allocator, where PyObject_New is inlined, and shows the important 180: distinction between two steps (at least): 181: 1) the actual allocation of the object storage; 182: 2) the initialization of the Python specific fields 183: in this storage with PyObject_{Init, InitVar}. 184: 185: PyObject * 186: YourObject_New(...) 187: { 188: PyObject *op; 189: 190: op = (PyObject *) Your_Allocator(_PyObject_SIZE(YourTypeStruct)); 191: if (op == NULL) 192: return PyErr_NoMemory(); 193: 194: PyObject_Init(op, &YourTypeStruct); 195: 196: op->ob_field = value; 197: ... 198: return op; 199: } 200: 201: Note that in C++, the use of the new operator usually implies that 202: the 1st step is performed automatically for you, so in a C++ class 203: constructor you would start directly with PyObject_Init/InitVar 204: */ 205: 206: #ifndef Py_LIMITED_API 207: typedef struct { 208: /* user context passed as the first argument to the 2 functions */ 209: void *ctx; 210: 211: /* allocate an arena of size bytes */ 212: void* (*alloc) (void *ctx, size_t size); 213: 214: /* free an arena */ 215: void (*free) (void *ctx, void *ptr, size_t size); 216: } PyObjectArenaAllocator; 217: 218: /* Get the arena allocator. */ 219: PyAPI_FUNC(void) PyObject_GetArenaAllocator(PyObjectArenaAllocator *allocator); 220: 221: /* Set the arena allocator. */ 222: PyAPI_FUNC(void) PyObject_SetArenaAllocator(PyObjectArenaAllocator *allocator); 223: #endif 224: 225: 226: /* 227: * Garbage Collection Support 228: * ========================== 229: */ 230: 231: /* C equivalent of gc.collect() which ignores the state of gc.enabled. */ 232: PyAPI_FUNC(Py_ssize_t) PyGC_Collect(void); 233: 234: #ifndef Py_LIMITED_API 235: PyAPI_FUNC(Py_ssize_t) _PyGC_CollectNoFail(void); 236: PyAPI_FUNC(Py_ssize_t) _PyGC_CollectIfEnabled(void); 237: #endif 238: 239: /* Test if a type has a GC head */ 240: #define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC) 241: 242: /* Test if an object has a GC head */ 243: #define PyObject_IS_GC(o) (PyType_IS_GC(Py_TYPE(o)) && \ 244: (Py_TYPE(o)->tp_is_gc == NULL || Py_TYPE(o)->tp_is_gc(o))) 245: 246: PyAPI_FUNC(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, Py_ssize_t); 247: #define PyObject_GC_Resize(type, op, n) \ 248: ( (type *) _PyObject_GC_Resize((PyVarObject *)(op), (n)) ) 249: 250: /* GC information is stored BEFORE the object structure. */ 251: #ifndef Py_LIMITED_API 252: typedef union _gc_head { 253: struct { 254: union _gc_head *gc_next; 255: union _gc_head *gc_prev; 256: Py_ssize_t gc_refs; 257: } gc; 258: double dummy; /* force worst-case alignment */ 259: } PyGC_Head; 260: 261: extern PyGC_Head *_PyGC_generation0; 262: 263: #define _Py_AS_GC(o) ((PyGC_Head *)(o)-1) 264: 265: /* Bit 0 is set when tp_finalize is called */ 266: #define _PyGC_REFS_MASK_FINALIZED (1 << 0) 267: /* The (N-1) most significant bits contain the gc state / refcount */ 268: #define _PyGC_REFS_SHIFT (1) 269: #define _PyGC_REFS_MASK (((size_t) -1) << _PyGC_REFS_SHIFT) 270: 271: #define _PyGCHead_REFS(g) ((g)->gc.gc_refs >> _PyGC_REFS_SHIFT) 272: #define _PyGCHead_SET_REFS(g, v) do { \ 273: (g)->gc.gc_refs = ((g)->gc.gc_refs & ~_PyGC_REFS_MASK) \ 274: | (((size_t)(v)) << _PyGC_REFS_SHIFT); \ 275: } while (0) 276: #define _PyGCHead_DECREF(g) ((g)->gc.gc_refs -= 1 << _PyGC_REFS_SHIFT) 277: 278: #define _PyGCHead_FINALIZED(g) (((g)->gc.gc_refs & _PyGC_REFS_MASK_FINALIZED) != 0) 279: #define _PyGCHead_SET_FINALIZED(g, v) do { \ 280: (g)->gc.gc_refs = ((g)->gc.gc_refs & ~_PyGC_REFS_MASK_FINALIZED) \ 281: | (v != 0); \ 282: } while (0) 283: 284: #define _PyGC_FINALIZED(o) _PyGCHead_FINALIZED(_Py_AS_GC(o)) 285: #define _PyGC_SET_FINALIZED(o, v) _PyGCHead_SET_FINALIZED(_Py_AS_GC(o), v) 286: 287: #define _PyGC_REFS(o) _PyGCHead_REFS(_Py_AS_GC(o)) 288: 289: #define _PyGC_REFS_UNTRACKED (-2) 290: #define _PyGC_REFS_REACHABLE (-3) 291: #define _PyGC_REFS_TENTATIVELY_UNREACHABLE (-4) 292: 293: /* Tell the GC to track this object. NB: While the object is tracked the 294: * collector it must be safe to call the ob_traverse method. */ 295: #define _PyObject_GC_TRACK(o) do { \ 296: PyGC_Head *g = _Py_AS_GC(o); \ 297: if (_PyGCHead_REFS(g) != _PyGC_REFS_UNTRACKED) \ 298: Py_FatalError("GC object already tracked"); \ 299: _PyGCHead_SET_REFS(g, _PyGC_REFS_REACHABLE); \ 300: g->gc.gc_next = _PyGC_generation0; \ 301: g->gc.gc_prev = _PyGC_generation0->gc.gc_prev; \ 302: g->gc.gc_prev->gc.gc_next = g; \ 303: _PyGC_generation0->gc.gc_prev = g; \ 304: } while (0); 305: 306: /* Tell the GC to stop tracking this object. 307: * gc_next doesn't need to be set to NULL, but doing so is a good 308: * way to provoke memory errors if calling code is confused. 309: */ 310: #define _PyObject_GC_UNTRACK(o) do { \ 311: PyGC_Head *g = _Py_AS_GC(o); \ 312: assert(_PyGCHead_REFS(g) != _PyGC_REFS_UNTRACKED); \ 313: _PyGCHead_SET_REFS(g, _PyGC_REFS_UNTRACKED); \ 314: g->gc.gc_prev->gc.gc_next = g->gc.gc_next; \ 315: g->gc.gc_next->gc.gc_prev = g->gc.gc_prev; \ 316: g->gc.gc_next = NULL; \ 317: } while (0); 318: 319: /* True if the object is currently tracked by the GC. */ 320: #define _PyObject_GC_IS_TRACKED(o) \ 321: (_PyGC_REFS(o) != _PyGC_REFS_UNTRACKED) 322: 323: /* True if the object may be tracked by the GC in the future, or already is. 324: This can be useful to implement some optimizations. */ 325: #define _PyObject_GC_MAY_BE_TRACKED(obj) \ 326: (PyObject_IS_GC(obj) && \ 327: (!PyTuple_CheckExact(obj) || _PyObject_GC_IS_TRACKED(obj))) 328: #endif /* Py_LIMITED_API */ 329: 330: #ifndef Py_LIMITED_API 331: PyAPI_FUNC(PyObject *) _PyObject_GC_Malloc(size_t size); 332: PyAPI_FUNC(PyObject *) _PyObject_GC_Calloc(size_t size); 333: #endif /* !Py_LIMITED_API */ 334: PyAPI_FUNC(PyObject *) _PyObject_GC_New(PyTypeObject *); 335: PyAPI_FUNC(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, Py_ssize_t); 336: PyAPI_FUNC(void) PyObject_GC_Track(void *); 337: PyAPI_FUNC(void) PyObject_GC_UnTrack(void *); 338: PyAPI_FUNC(void) PyObject_GC_Del(void *); 339: 340: #define PyObject_GC_New(type, typeobj) \ 341: ( (type *) _PyObject_GC_New(typeobj) ) 342: #define PyObject_GC_NewVar(type, typeobj, n) \ 343: ( (type *) _PyObject_GC_NewVar((typeobj), (n)) ) 344: 345: 346: /* Utility macro to help write tp_traverse functions. 347: * To use this macro, the tp_traverse function must name its arguments 348: * "visit" and "arg". This is intended to keep tp_traverse functions 349: * looking as much alike as possible. 350: */ 351: #define Py_VISIT(op) \ 352: do { \ 353: if (op) { \ 354: int vret = visit((PyObject *)(op), arg); \ 355: if (vret) \ 356: return vret; \ 357: } \ 358: } while (0) 359: 360: 361: /* Test if a type supports weak references */ 362: #define PyType_SUPPORTS_WEAKREFS(t) ((t)->tp_weaklistoffset > 0) 363: 364: #define PyObject_GET_WEAKREFS_LISTPTR(o) \ 365: ((PyObject **) (((char *) (o)) + Py_TYPE(o)->tp_weaklistoffset)) 366: 367: #ifdef __cplusplus 368: } 369: #endif 370: #endif /* !Py_OBJIMPL_H */ 371: