mirror of
https://github.com/python/cpython.git
synced 2024-11-25 01:20:47 +01:00
292 lines
11 KiB
C
292 lines
11 KiB
C
|
|
#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 actually
|
|
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.
|
|
|
|
- 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
|
|
within the Python heap by an object allocator, the latter being
|
|
implemented (by default) on top of the Python raw memory
|
|
allocator. This ensures that Python keeps control on the user's
|
|
objects regarding their memory management; for instance, they may be
|
|
subject to automatic garbage collection.
|
|
|
|
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}. */
|
|
|
|
/*
|
|
* Core object memory allocator
|
|
* ============================
|
|
*/
|
|
|
|
/* The purpose of the object allocator is to make the distinction
|
|
between "object memory" and the rest within the Python heap.
|
|
|
|
Object memory is the one allocated by PyObject_{New, NewVar}, i.e.
|
|
the one that holds the object's representation defined by its C
|
|
type structure, *excluding* any object-specific memory buffers that
|
|
might be referenced by the structure (for type structures that have
|
|
pointer fields). By default, the object memory allocator is
|
|
implemented on top of the raw memory allocator.
|
|
|
|
The PyCore_* macros can be defined to make the interpreter use a
|
|
custom object memory allocator. They are reserved for internal
|
|
memory management purposes exclusively. Both the core and extension
|
|
modules should use the PyObject_* API. */
|
|
|
|
#ifdef WITH_PYMALLOC
|
|
#define PyCore_OBJECT_MALLOC_FUNC _PyCore_ObjectMalloc
|
|
#define PyCore_OBJECT_REALLOC_FUNC _PyCore_ObjectRealloc
|
|
#define PyCore_OBJECT_FREE_FUNC _PyCore_ObjectFree
|
|
#define NEED_TO_DECLARE_OBJECT_MALLOC_AND_FRIEND
|
|
#endif /* !WITH_PYMALLOC */
|
|
|
|
#ifndef PyCore_OBJECT_MALLOC_FUNC
|
|
#undef PyCore_OBJECT_REALLOC_FUNC
|
|
#undef PyCore_OBJECT_FREE_FUNC
|
|
#define PyCore_OBJECT_MALLOC_FUNC PyCore_MALLOC_FUNC
|
|
#define PyCore_OBJECT_REALLOC_FUNC PyCore_REALLOC_FUNC
|
|
#define PyCore_OBJECT_FREE_FUNC PyCore_FREE_FUNC
|
|
#endif
|
|
|
|
#ifndef PyCore_OBJECT_MALLOC_PROTO
|
|
#undef PyCore_OBJECT_REALLOC_PROTO
|
|
#undef PyCore_OBJECT_FREE_PROTO
|
|
#define PyCore_OBJECT_MALLOC_PROTO PyCore_MALLOC_PROTO
|
|
#define PyCore_OBJECT_REALLOC_PROTO PyCore_REALLOC_PROTO
|
|
#define PyCore_OBJECT_FREE_PROTO PyCore_FREE_PROTO
|
|
#endif
|
|
|
|
#ifdef NEED_TO_DECLARE_OBJECT_MALLOC_AND_FRIEND
|
|
extern void *PyCore_OBJECT_MALLOC_FUNC PyCore_OBJECT_MALLOC_PROTO;
|
|
extern void *PyCore_OBJECT_REALLOC_FUNC PyCore_OBJECT_REALLOC_PROTO;
|
|
extern void PyCore_OBJECT_FREE_FUNC PyCore_OBJECT_FREE_PROTO;
|
|
#endif
|
|
|
|
#ifndef PyCore_OBJECT_MALLOC
|
|
#undef PyCore_OBJECT_REALLOC
|
|
#undef PyCore_OBJECT_FREE
|
|
#define PyCore_OBJECT_MALLOC(n) PyCore_OBJECT_MALLOC_FUNC(n)
|
|
#define PyCore_OBJECT_REALLOC(p, n) PyCore_OBJECT_REALLOC_FUNC((p), (n))
|
|
#define PyCore_OBJECT_FREE(p) PyCore_OBJECT_FREE_FUNC(p)
|
|
#endif
|
|
|
|
/*
|
|
* 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 */
|
|
|
|
/* Wrappers around PyCore_OBJECT_MALLOC and friends; useful if you
|
|
need to be sure that you are using the same object memory allocator
|
|
as Python. These wrappers *do not* make sure that allocating 0
|
|
bytes returns a non-NULL pointer. Returned pointers must be checked
|
|
for NULL explicitly; no action is performed on failure. */
|
|
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 */
|
|
#define PyObject_MALLOC(n) PyCore_OBJECT_MALLOC(n)
|
|
#define PyObject_REALLOC(op, n) PyCore_OBJECT_REALLOC((void *)(op), (n))
|
|
#define PyObject_FREE(op) PyCore_OBJECT_FREE((void *)(op))
|
|
|
|
/*
|
|
* 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);
|
|
extern DL_IMPORT(void) _PyObject_Del(PyObject *);
|
|
|
|
#define PyObject_New(type, typeobj) \
|
|
( (type *) _PyObject_New(typeobj) )
|
|
#define PyObject_NewVar(type, typeobj, n) \
|
|
( (type *) _PyObject_NewVar((typeobj), (n)) )
|
|
#define PyObject_Del(op) _PyObject_Del((PyObject *)(op))
|
|
|
|
/* 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)), \
|
|
(PyType_SUPPORTS_WEAKREFS((typeobj)) \
|
|
? *(PyObject_GET_WEAKREFS_LISTPTR(op)) = NULL \
|
|
: NULL), \
|
|
(op))
|
|
#define PyObject_INIT_VAR(op, typeobj, size) \
|
|
( (op)->ob_size = (size), PyObject_INIT((op), (typeobj)) )
|
|
|
|
#define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize )
|
|
#define _PyObject_VAR_SIZE(typeobj, n) \
|
|
( (typeobj)->tp_basicsize + (n) * (typeobj)->tp_itemsize )
|
|
|
|
#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)) )
|
|
|
|
#define PyObject_DEL(op) PyObject_FREE(op)
|
|
|
|
/* 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
|
|
* ==========================
|
|
*/
|
|
|
|
/* To make a new object participate in garbage collection use
|
|
PyObject_{New, VarNew, Del} to manage the memory. Set the type flag
|
|
Py_TPFLAGS_GC and define the type method tp_traverse. You should also
|
|
add the method tp_clear if your object is mutable. Include
|
|
PyGC_HEAD_SIZE in the calculation of tp_basicsize. Call
|
|
PyObject_GC_Init after the pointers followed by tp_traverse become
|
|
valid (usually just before returning the object from the allocation
|
|
method. Call PyObject_GC_Fini before those pointers become invalid
|
|
(usually at the top of the deallocation method). */
|
|
|
|
#ifndef WITH_CYCLE_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)
|
|
|
|
#else
|
|
|
|
/* Add the object into the container set */
|
|
extern DL_IMPORT(void) _PyGC_Insert(PyObject *);
|
|
|
|
/* Remove the object from the container set */
|
|
extern DL_IMPORT(void) _PyGC_Remove(PyObject *);
|
|
|
|
#define PyObject_GC_Init(op) _PyGC_Insert((PyObject *)op)
|
|
#define PyObject_GC_Fini(op) _PyGC_Remove((PyObject *)op)
|
|
|
|
/* Structure *prefixed* to container objects participating in GC */
|
|
typedef struct _gc_head {
|
|
struct _gc_head *gc_next;
|
|
struct _gc_head *gc_prev;
|
|
int gc_refs;
|
|
} PyGC_Head;
|
|
|
|
#define PyGC_HEAD_SIZE sizeof(PyGC_Head)
|
|
|
|
/* Test if a type has a GC head */
|
|
#define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_GC)
|
|
|
|
/* Test if an object has a GC head */
|
|
#define PyObject_IS_GC(o) PyType_IS_GC((o)->ob_type)
|
|
|
|
/* Get an object's GC head */
|
|
#define PyObject_AS_GC(o) ((PyGC_Head *)(o)-1)
|
|
|
|
/* Get the object given the PyGC_Head */
|
|
#define PyObject_FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1))
|
|
|
|
extern DL_IMPORT(void) _PyGC_Dump(PyGC_Head *);
|
|
|
|
#endif /* WITH_CYCLE_GC */
|
|
|
|
/* 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 */
|