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 has 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); 103 104 105 /* Macros */ 106 #define PyObject_MALLOC PyObject_Malloc 107 #define PyObject_REALLOC PyObject_Realloc 108 #define PyObject_FREE PyObject_Free 109 #define PyObject_Del PyObject_Free 110 #define PyObject_DEL PyObject_Free 111 112 113 /* 114 * Generic object allocator interface 115 * ================================== 116 */ 117 118 /* Functions */ 119 PyAPI_FUNC(PyObject *) PyObject_Init(PyObject *, PyTypeObject *); 120 PyAPI_FUNC(PyVarObject *) PyObject_InitVar(PyVarObject *, 121 PyTypeObject *, Py_ssize_t); 122 PyAPI_FUNC(PyObject *) _PyObject_New(PyTypeObject *); 123 PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t); 124 125 #define PyObject_New(type, typeobj) ((type *)_PyObject_New(typeobj)) 126 127 // Alias to PyObject_New(). In Python 3.8, PyObject_NEW() called directly 128 // PyObject_MALLOC() with _PyObject_SIZE(). 129 #define PyObject_NEW(type, typeobj) PyObject_New(type, typeobj) 130 131 #define PyObject_NewVar(type, typeobj, n) \ 132 ( (type *) _PyObject_NewVar((typeobj), (n)) ) 133 134 // Alias to PyObject_New(). In Python 3.8, PyObject_NEW() called directly 135 // PyObject_MALLOC() with _PyObject_VAR_SIZE(). 136 #define PyObject_NEW_VAR(type, typeobj, n) PyObject_NewVar(type, typeobj, n) 137 138 139 #ifdef Py_LIMITED_API 140 /* Define PyObject_INIT() and PyObject_INIT_VAR() as aliases to PyObject_Init() 141 and PyObject_InitVar() in the limited C API for compatibility with the 142 CPython C API. */ 143 # define PyObject_INIT(op, typeobj) \ 144 PyObject_Init(_PyObject_CAST(op), (typeobj)) 145 # define PyObject_INIT_VAR(op, typeobj, size) \ 146 PyObject_InitVar(_PyVarObject_CAST(op), (typeobj), (size)) 147 #else 148 /* PyObject_INIT() and PyObject_INIT_VAR() are defined in cpython/objimpl.h */ 149 #endif 150 151 152 /* 153 * Garbage Collection Support 154 * ========================== 155 */ 156 157 /* C equivalent of gc.collect() which ignores the state of gc.enabled. */ 158 PyAPI_FUNC(Py_ssize_t) PyGC_Collect(void); 159 160 /* Test if a type has a GC head */ 161 #define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC) 162 163 PyAPI_FUNC(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, Py_ssize_t); 164 #define PyObject_GC_Resize(type, op, n) \ 165 ( (type *) _PyObject_GC_Resize(_PyVarObject_CAST(op), (n)) ) 166 167 168 169 PyAPI_FUNC(PyObject *) _PyObject_GC_New(PyTypeObject *); 170 PyAPI_FUNC(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, Py_ssize_t); 171 172 /* Tell the GC to track this object. 173 * 174 * See also private _PyObject_GC_TRACK() macro. */ 175 PyAPI_FUNC(void) PyObject_GC_Track(void *); 176 177 /* Tell the GC to stop tracking this object. 178 * 179 * See also private _PyObject_GC_UNTRACK() macro. */ 180 PyAPI_FUNC(void) PyObject_GC_UnTrack(void *); 181 182 PyAPI_FUNC(void) PyObject_GC_Del(void *); 183 184 #define PyObject_GC_New(type, typeobj) \ 185 ( (type *) _PyObject_GC_New(typeobj) ) 186 #define PyObject_GC_NewVar(type, typeobj, n) \ 187 ( (type *) _PyObject_GC_NewVar((typeobj), (n)) ) 188 189 PyAPI_FUNC(int) PyObject_GC_IsTracked(PyObject *); 190 PyAPI_FUNC(int) PyObject_GC_IsFinalized(PyObject *); 191 192 /* Utility macro to help write tp_traverse functions. 193 * To use this macro, the tp_traverse function must name its arguments 194 * "visit" and "arg". This is intended to keep tp_traverse functions 195 * looking as much alike as possible. 196 */ 197 #define Py_VISIT(op) \ 198 do { \ 199 if (op) { \ 200 int vret = visit(_PyObject_CAST(op), arg); \ 201 if (vret) \ 202 return vret; \ 203 } \ 204 } while (0) 205 206 #ifndef Py_LIMITED_API 207 # define Py_CPYTHON_OBJIMPL_H 208 # include "cpython/objimpl.h" 209 # undef Py_CPYTHON_OBJIMPL_H 210 #endif 211 212 #ifdef __cplusplus 213 } 214 #endif 215 #endif /* !Py_OBJIMPL_H */ 216