Chris@87: /* An arena-like memory interface for the compiler.
Chris@87:  */
Chris@87: 
Chris@87: #ifndef Py_PYARENA_H
Chris@87: #define Py_PYARENA_H
Chris@87: 
Chris@87: #ifdef __cplusplus
Chris@87: extern "C" {
Chris@87: #endif
Chris@87: 
Chris@87:   typedef struct _arena PyArena;
Chris@87: 
Chris@87:   /* PyArena_New() and PyArena_Free() create a new arena and free it,
Chris@87:      respectively.  Once an arena has been created, it can be used
Chris@87:      to allocate memory via PyArena_Malloc().  Pointers to PyObject can
Chris@87:      also be registered with the arena via PyArena_AddPyObject(), and the
Chris@87:      arena will ensure that the PyObjects stay alive at least until
Chris@87:      PyArena_Free() is called.  When an arena is freed, all the memory it
Chris@87:      allocated is freed, the arena releases internal references to registered
Chris@87:      PyObject*, and none of its pointers are valid.
Chris@87:      XXX (tim) What does "none of its pointers are valid" mean?  Does it
Chris@87:      XXX mean that pointers previously obtained via PyArena_Malloc() are
Chris@87:      XXX no longer valid?  (That's clearly true, but not sure that's what
Chris@87:      XXX the text is trying to say.)
Chris@87: 
Chris@87:      PyArena_New() returns an arena pointer.  On error, it
Chris@87:      returns a negative number and sets an exception.
Chris@87:      XXX (tim):  Not true.  On error, PyArena_New() actually returns NULL,
Chris@87:      XXX and looks like it may or may not set an exception (e.g., if the
Chris@87:      XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on
Chris@87:      XXX and an exception is set; OTOH, if the internal
Chris@87:      XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but
Chris@87:      XXX an exception is not set in that case).
Chris@87:   */
Chris@87:   PyAPI_FUNC(PyArena *) PyArena_New(void);
Chris@87:   PyAPI_FUNC(void) PyArena_Free(PyArena *);
Chris@87: 
Chris@87:   /* Mostly like malloc(), return the address of a block of memory spanning
Chris@87:    * `size` bytes, or return NULL (without setting an exception) if enough
Chris@87:    * new memory can't be obtained.  Unlike malloc(0), PyArena_Malloc() with
Chris@87:    * size=0 does not guarantee to return a unique pointer (the pointer
Chris@87:    * returned may equal one or more other pointers obtained from
Chris@87:    * PyArena_Malloc()).
Chris@87:    * Note that pointers obtained via PyArena_Malloc() must never be passed to
Chris@87:    * the system free() or realloc(), or to any of Python's similar memory-
Chris@87:    * management functions.  PyArena_Malloc()-obtained pointers remain valid
Chris@87:    * until PyArena_Free(ar) is called, at which point all pointers obtained
Chris@87:    * from the arena `ar` become invalid simultaneously.
Chris@87:    */
Chris@87:   PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);
Chris@87: 
Chris@87:   /* This routine isn't a proper arena allocation routine.  It takes
Chris@87:    * a PyObject* and records it so that it can be DECREFed when the
Chris@87:    * arena is freed.
Chris@87:    */
Chris@87:   PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);
Chris@87: 
Chris@87: #ifdef __cplusplus
Chris@87: }
Chris@87: #endif
Chris@87: 
Chris@87: #endif /* !Py_PYARENA_H */