1 // The PyObject_ memory family: high-level object memory interfaces. 2 // See pymem.h for the low-level PyMem_ family. 3 4 #ifndef Py_OBJIMPL_H 5 #define Py_OBJIMPL_H 6 #ifdef __cplusplus 7 extern "C" { 8 #endif 9 10 /* BEWARE: 11 12 Each interface exports both functions and macros. Extension modules should 13 use the functions, to ensure binary compatibility across Python versions. 14 Because the Python implementation is free to change internal details, and 15 the macros may (or may not) expose details for speed, if you do use the 16 macros you must recompile your extensions with each Python release. 17 18 Never mix calls to PyObject_ memory functions with calls to the platform 19 malloc/realloc/ calloc/free, or with calls to PyMem_. 20 */ 21 22 /* 23 Functions and macros for modules that implement new object types. 24 25 - PyObject_New(type, typeobj) allocates memory for a new object of the given 26 type, and initializes part of it. 'type' must be the C structure type used 27 to represent the object, and 'typeobj' the address of the corresponding 28 type object. Reference count and type pointer are filled in; the rest of 29 the bytes of the object are *undefined*! The resulting expression type is 30 'type *'. The size of the object is determined by the tp_basicsize field 31 of the type object. 32 33 - PyObject_NewVar(type, typeobj, n) is similar but allocates a variable-size 34 object with room for n items. In addition to the refcount and type pointer 35 fields, this also fills in the ob_size field. 36 37 - PyObject_Free(op) releases the memory allocated for an object. It does not 38 run a destructor -- it only frees the memory. 39 40 - PyObject_Init(op, typeobj) and PyObject_InitVar(op, typeobj, n) don't 41 allocate memory. Instead of a 'type' parameter, they take a pointer to a 42 new object (allocated by an arbitrary allocator), and initialize its object 43 header fields. 44 45 Note that objects created with PyObject_{New, NewVar} are allocated using the 46 specialized Python allocator (implemented in obmalloc.c), if WITH_PYMALLOC is 47 enabled. In addition, a special debugging allocator is used if Py_DEBUG 48 macro is also defined. 49 50 In case a specific form of memory management is needed (for example, if you 51 must use the platform malloc heap(s), or shared memory, or C++ local storage or 52 operator new), you must first allocate the object with your custom allocator, 53 then pass its pointer to PyObject_{Init, InitVar} for filling in its Python- 54 specific fields: reference count, type pointer, possibly others. You should 55 be aware that Python has no control over these objects because they don't 56 cooperate with the Python memory manager. Such objects may not be eligible 57 for automatic garbage collection and you have to make sure that they are 58 released accordingly whenever their destructor gets called (cf. the specific 59 form of memory management you're using). 60 61 Unless you have specific memory management requirements, use 62 PyObject_{New, NewVar, Del}. 63 */ 64 65 /* 66 * Raw object memory interface 67 * =========================== 68 */ 69 70 /* Functions to call the same malloc/realloc/free as used by Python's 71 object allocator. If WITH_PYMALLOC is enabled, these may differ from 72 the platform malloc/realloc/free. The Python object allocator is 73 designed for fast, cache-conscious allocation of many "small" objects, 74 and with low hidden memory overhead. 75 76 PyObject_Malloc(0) returns a unique non-NULL pointer if possible. 77 78 PyObject_Realloc(NULL, n) acts like PyObject_Malloc(n). 79 PyObject_Realloc(p != NULL, 0) does not return NULL, or free the memory 80 at p. 81 82 Returned pointers must be checked for NULL explicitly; no action is 83 performed on failure other than to return NULL (no warning it printed, no 84 exception is set, etc). 85 86 For allocating objects, use PyObject_{New, NewVar} instead whenever 87 possible. The PyObject_{Malloc, Realloc, Free} family is exposed 88 so that you can exploit Python's small-block allocator for non-object 89 uses. If you must use these routines to allocate object memory, make sure 90 the object gets initialized via PyObject_{Init, InitVar} after obtaining 91 the raw memory. 92 */ 93 PyAPI_FUNC(void *) PyObject_Malloc(size_t size); 94 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03050000 95 PyAPI_FUNC(void *) PyObject_Calloc(size_t nelem, size_t elsize); 96 #endif 97 PyAPI_FUNC(void *) PyObject_Realloc(void *ptr, size_t new_size); 98 PyAPI_FUNC(void) PyObject_Free(void *ptr); 99 100 101 // Deprecated aliases only kept for backward compatibility. 102 // PyObject_Del and PyObject_DEL are defined with no parameter to be able to 103 // use them as function pointers (ex: tp_free = PyObject_Del). 104 #define PyObject_MALLOC PyObject_Malloc 105 #define PyObject_REALLOC PyObject_Realloc 106 #define PyObject_FREE PyObject_Free 107 #define PyObject_Del PyObject_Free 108 #define PyObject_DEL PyObject_Free 109 110 111 /* 112 * Generic object allocator interface 113 * ================================== 114 */ 115 116 /* Functions */ 117 PyAPI_FUNC(PyObject *) PyObject_Init(PyObject *, PyTypeObject *); 118 PyAPI_FUNC(PyVarObject *) PyObject_InitVar(PyVarObject *, 119 PyTypeObject *, Py_ssize_t); 120 121 #define PyObject_INIT(op, typeobj) \ 122 PyObject_Init(_PyObject_CAST(op), (typeobj)) 123 #define PyObject_INIT_VAR(op, typeobj, size) \ 124 PyObject_InitVar(_PyVarObject_CAST(op), (typeobj), (size)) 125 126 127 PyAPI_FUNC(PyObject *) _PyObject_New(PyTypeObject *); 128 PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t); 129 130 #define PyObject_New(type, typeobj) ((type *)_PyObject_New(typeobj)) 131 132 // Alias to PyObject_New(). In Python 3.8, PyObject_NEW() called directly 133 // PyObject_MALLOC() with _PyObject_SIZE(). 134 #define PyObject_NEW(type, typeobj) PyObject_New(type, (typeobj)) 135 136 #define PyObject_NewVar(type, typeobj, n) \ 137 ( (type *) _PyObject_NewVar((typeobj), (n)) ) 138 139 // Alias to PyObject_NewVar(). In Python 3.8, PyObject_NEW_VAR() called 140 // directly PyObject_MALLOC() with _PyObject_VAR_SIZE(). 141 #define PyObject_NEW_VAR(type, typeobj, n) PyObject_NewVar(type, (typeobj), (n)) 142 143 144 /* 145 * Garbage Collection Support 146 * ========================== 147 */ 148 149 /* C equivalent of gc.collect(). */ 150 PyAPI_FUNC(Py_ssize_t) PyGC_Collect(void); 151 /* C API for controlling the state of the garbage collector */ 152 PyAPI_FUNC(int) PyGC_Enable(void); 153 PyAPI_FUNC(int) PyGC_Disable(void); 154 PyAPI_FUNC(int) PyGC_IsEnabled(void); 155 156 /* Test if a type has a GC head */ 157 #define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC) 158 159 PyAPI_FUNC(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, Py_ssize_t); 160 #define PyObject_GC_Resize(type, op, n) \ 161 ( (type *) _PyObject_GC_Resize(_PyVarObject_CAST(op), (n)) ) 162 163 164 165 PyAPI_FUNC(PyObject *) _PyObject_GC_New(PyTypeObject *); 166 PyAPI_FUNC(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, Py_ssize_t); 167 168 /* Tell the GC to track this object. 169 * 170 * See also private _PyObject_GC_TRACK() macro. */ 171 PyAPI_FUNC(void) PyObject_GC_Track(void *); 172 173 /* Tell the GC to stop tracking this object. 174 * 175 * See also private _PyObject_GC_UNTRACK() macro. */ 176 PyAPI_FUNC(void) PyObject_GC_UnTrack(void *); 177 178 PyAPI_FUNC(void) PyObject_GC_Del(void *); 179 180 #define PyObject_GC_New(type, typeobj) \ 181 _Py_CAST(type*, _PyObject_GC_New(typeobj)) 182 #define PyObject_GC_NewVar(type, typeobj, n) \ 183 _Py_CAST(type*, _PyObject_GC_NewVar((typeobj), (n))) 184 185 PyAPI_FUNC(int) PyObject_GC_IsTracked(PyObject *); 186 PyAPI_FUNC(int) PyObject_GC_IsFinalized(PyObject *); 187 188 /* Utility macro to help write tp_traverse functions. 189 * To use this macro, the tp_traverse function must name its arguments 190 * "visit" and "arg". This is intended to keep tp_traverse functions 191 * looking as much alike as possible. 192 */ 193 #define Py_VISIT(op) \ 194 do { \ 195 if (op) { \ 196 int vret = visit(_PyObject_CAST(op), arg); \ 197 if (vret) \ 198 return vret; \ 199 } \ 200 } while (0) 201 202 #ifndef Py_LIMITED_API 203 # define Py_CPYTHON_OBJIMPL_H 204 # include "cpython/objimpl.h" 205 # undef Py_CPYTHON_OBJIMPL_H 206 #endif 207 208 #ifdef __cplusplus 209 } 210 #endif 211 #endif // !Py_OBJIMPL_H 212