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File indexing completed on 2025-11-19 09:50:54
0001 // The PyObject_ memory family: high-level object memory interfaces. 0002 // See pymem.h for the low-level PyMem_ family. 0003 0004 #ifndef Py_OBJIMPL_H 0005 #define Py_OBJIMPL_H 0006 #ifdef __cplusplus 0007 extern "C" { 0008 #endif 0009 0010 /* BEWARE: 0011 0012 Each interface exports both functions and macros. Extension modules should 0013 use the functions, to ensure binary compatibility across Python versions. 0014 Because the Python implementation is free to change internal details, and 0015 the macros may (or may not) expose details for speed, if you do use the 0016 macros you must recompile your extensions with each Python release. 0017 0018 Never mix calls to PyObject_ memory functions with calls to the platform 0019 malloc/realloc/ calloc/free, or with calls to PyMem_. 0020 */ 0021 0022 /* 0023 Functions and macros for modules that implement new object types. 0024 0025 - PyObject_New(type, typeobj) allocates memory for a new object of the given 0026 type, and initializes part of it. 'type' must be the C structure type used 0027 to represent the object, and 'typeobj' the address of the corresponding 0028 type object. Reference count and type pointer are filled in; the rest of 0029 the bytes of the object are *undefined*! The resulting expression type is 0030 'type *'. The size of the object is determined by the tp_basicsize field 0031 of the type object. 0032 0033 - PyObject_NewVar(type, typeobj, n) is similar but allocates a variable-size 0034 object with room for n items. In addition to the refcount and type pointer 0035 fields, this also fills in the ob_size field. 0036 0037 - PyObject_Free(op) releases the memory allocated for an object. It does not 0038 run a destructor -- it only frees the memory. 0039 0040 - PyObject_Init(op, typeobj) and PyObject_InitVar(op, typeobj, n) don't 0041 allocate memory. Instead of a 'type' parameter, they take a pointer to a 0042 new object (allocated by an arbitrary allocator), and initialize its object 0043 header fields. 0044 0045 Note that objects created with PyObject_{New, NewVar} are allocated using the 0046 specialized Python allocator (implemented in obmalloc.c), if WITH_PYMALLOC is 0047 enabled. In addition, a special debugging allocator is used if Py_DEBUG 0048 macro is also defined. 0049 0050 In case a specific form of memory management is needed (for example, if you 0051 must use the platform malloc heap(s), or shared memory, or C++ local storage or 0052 operator new), you must first allocate the object with your custom allocator, 0053 then pass its pointer to PyObject_{Init, InitVar} for filling in its Python- 0054 specific fields: reference count, type pointer, possibly others. You should 0055 be aware that Python has no control over these objects because they don't 0056 cooperate with the Python memory manager. Such objects may not be eligible 0057 for automatic garbage collection and you have to make sure that they are 0058 released accordingly whenever their destructor gets called (cf. the specific 0059 form of memory management you're using). 0060 0061 Unless you have specific memory management requirements, use 0062 PyObject_{New, NewVar, Del}. 0063 */ 0064 0065 /* 0066 * Raw object memory interface 0067 * =========================== 0068 */ 0069 0070 /* Functions to call the same malloc/realloc/free as used by Python's 0071 object allocator. If WITH_PYMALLOC is enabled, these may differ from 0072 the platform malloc/realloc/free. The Python object allocator is 0073 designed for fast, cache-conscious allocation of many "small" objects, 0074 and with low hidden memory overhead. 0075 0076 PyObject_Malloc(0) returns a unique non-NULL pointer if possible. 0077 0078 PyObject_Realloc(NULL, n) acts like PyObject_Malloc(n). 0079 PyObject_Realloc(p != NULL, 0) does not return NULL, or free the memory 0080 at p. 0081 0082 Returned pointers must be checked for NULL explicitly; no action is 0083 performed on failure other than to return NULL (no warning it printed, no 0084 exception is set, etc). 0085 0086 For allocating objects, use PyObject_{New, NewVar} instead whenever 0087 possible. The PyObject_{Malloc, Realloc, Free} family is exposed 0088 so that you can exploit Python's small-block allocator for non-object 0089 uses. If you must use these routines to allocate object memory, make sure 0090 the object gets initialized via PyObject_{Init, InitVar} after obtaining 0091 the raw memory. 0092 */ 0093 PyAPI_FUNC(void *) PyObject_Malloc(size_t size); 0094 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03050000 0095 PyAPI_FUNC(void *) PyObject_Calloc(size_t nelem, size_t elsize); 0096 #endif 0097 PyAPI_FUNC(void *) PyObject_Realloc(void *ptr, size_t new_size); 0098 PyAPI_FUNC(void) PyObject_Free(void *ptr); 0099 0100 0101 // Deprecated aliases only kept for backward compatibility. 0102 // PyObject_Del and PyObject_DEL are defined with no parameter to be able to 0103 // use them as function pointers (ex: tp_free = PyObject_Del). 0104 #define PyObject_MALLOC PyObject_Malloc 0105 #define PyObject_REALLOC PyObject_Realloc 0106 #define PyObject_FREE PyObject_Free 0107 #define PyObject_Del PyObject_Free 0108 #define PyObject_DEL PyObject_Free 0109 0110 0111 /* 0112 * Generic object allocator interface 0113 * ================================== 0114 */ 0115 0116 /* Functions */ 0117 PyAPI_FUNC(PyObject *) PyObject_Init(PyObject *, PyTypeObject *); 0118 PyAPI_FUNC(PyVarObject *) PyObject_InitVar(PyVarObject *, 0119 PyTypeObject *, Py_ssize_t); 0120 0121 #define PyObject_INIT(op, typeobj) \ 0122 PyObject_Init(_PyObject_CAST(op), (typeobj)) 0123 #define PyObject_INIT_VAR(op, typeobj, size) \ 0124 PyObject_InitVar(_PyVarObject_CAST(op), (typeobj), (size)) 0125 0126 0127 PyAPI_FUNC(PyObject *) _PyObject_New(PyTypeObject *); 0128 PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t); 0129 0130 #define PyObject_New(type, typeobj) ((type *)_PyObject_New(typeobj)) 0131 0132 // Alias to PyObject_New(). In Python 3.8, PyObject_NEW() called directly 0133 // PyObject_MALLOC() with _PyObject_SIZE(). 0134 #define PyObject_NEW(type, typeobj) PyObject_New(type, (typeobj)) 0135 0136 #define PyObject_NewVar(type, typeobj, n) \ 0137 ( (type *) _PyObject_NewVar((typeobj), (n)) ) 0138 0139 // Alias to PyObject_NewVar(). In Python 3.8, PyObject_NEW_VAR() called 0140 // directly PyObject_MALLOC() with _PyObject_VAR_SIZE(). 0141 #define PyObject_NEW_VAR(type, typeobj, n) PyObject_NewVar(type, (typeobj), (n)) 0142 0143 0144 /* 0145 * Garbage Collection Support 0146 * ========================== 0147 */ 0148 0149 /* C equivalent of gc.collect(). */ 0150 PyAPI_FUNC(Py_ssize_t) PyGC_Collect(void); 0151 /* C API for controlling the state of the garbage collector */ 0152 PyAPI_FUNC(int) PyGC_Enable(void); 0153 PyAPI_FUNC(int) PyGC_Disable(void); 0154 PyAPI_FUNC(int) PyGC_IsEnabled(void); 0155 0156 /* Test if a type has a GC head */ 0157 #define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC) 0158 0159 PyAPI_FUNC(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, Py_ssize_t); 0160 #define PyObject_GC_Resize(type, op, n) \ 0161 ( (type *) _PyObject_GC_Resize(_PyVarObject_CAST(op), (n)) ) 0162 0163 0164 0165 PyAPI_FUNC(PyObject *) _PyObject_GC_New(PyTypeObject *); 0166 PyAPI_FUNC(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, Py_ssize_t); 0167 0168 /* Tell the GC to track this object. 0169 * 0170 * See also private _PyObject_GC_TRACK() macro. */ 0171 PyAPI_FUNC(void) PyObject_GC_Track(void *); 0172 0173 /* Tell the GC to stop tracking this object. 0174 * 0175 * See also private _PyObject_GC_UNTRACK() macro. */ 0176 PyAPI_FUNC(void) PyObject_GC_UnTrack(void *); 0177 0178 PyAPI_FUNC(void) PyObject_GC_Del(void *); 0179 0180 #define PyObject_GC_New(type, typeobj) \ 0181 _Py_CAST(type*, _PyObject_GC_New(typeobj)) 0182 #define PyObject_GC_NewVar(type, typeobj, n) \ 0183 _Py_CAST(type*, _PyObject_GC_NewVar((typeobj), (n))) 0184 0185 PyAPI_FUNC(int) PyObject_GC_IsTracked(PyObject *); 0186 PyAPI_FUNC(int) PyObject_GC_IsFinalized(PyObject *); 0187 0188 /* Utility macro to help write tp_traverse functions. 0189 * To use this macro, the tp_traverse function must name its arguments 0190 * "visit" and "arg". This is intended to keep tp_traverse functions 0191 * looking as much alike as possible. 0192 */ 0193 #define Py_VISIT(op) \ 0194 do { \ 0195 if (op) { \ 0196 int vret = visit(_PyObject_CAST(op), arg); \ 0197 if (vret) \ 0198 return vret; \ 0199 } \ 0200 } while (0) 0201 0202 #ifndef Py_LIMITED_API 0203 # define Py_CPYTHON_OBJIMPL_H 0204 # include "cpython/objimpl.h" 0205 # undef Py_CPYTHON_OBJIMPL_H 0206 #endif 0207 0208 #ifdef __cplusplus 0209 } 0210 #endif 0211 #endif // !Py_OBJIMPL_H
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