blob: 5f193feceeaa25bd8644454156703b680d63db59 [file] [log] [blame]
/* An arena-like memory interface for the compiler.
#ifndef Py_PYARENA_H
#define Py_PYARENA_H
#ifdef __cplusplus
extern "C" {
typedef struct _arena PyArena;
/* PyArena_New() and PyArena_Free() create a new arena and free it,
respectively. Once an arena has been created, it can be used
to allocate memory via PyArena_Malloc(). Pointers to PyObject can
also be registered with the arena via PyArena_AddPyObject(), and the
arena will ensure that the PyObjects stay alive at least until
PyArena_Free() is called. When an arena is freed, all the memory it
allocated is freed, the arena releases internal references to registered
PyObject*, and none of its pointers are valid.
XXX (tim) What does "none of its pointers are valid" mean? Does it
XXX mean that pointers previously obtained via PyArena_Malloc() are
XXX no longer valid? (That's clearly true, but not sure that's what
XXX the text is trying to say.)
PyArena_New() returns an arena pointer. On error, it
returns a negative number and sets an exception.
XXX (tim): Not true. On error, PyArena_New() actually returns NULL,
XXX and looks like it may or may not set an exception (e.g., if the
XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on
XXX and an exception is set; OTOH, if the internal
XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but
XXX an exception is not set in that case).
PyAPI_FUNC(PyArena *) PyArena_New(void);
PyAPI_FUNC(void) PyArena_Free(PyArena *);
/* Mostly like malloc(), return the address of a block of memory spanning
* `size` bytes, or return NULL (without setting an exception) if enough
* new memory can't be obtained. Unlike malloc(0), PyArena_Malloc() with
* size=0 does not guarantee to return a unique pointer (the pointer
* returned may equal one or more other pointers obtained from
* PyArena_Malloc()).
* Note that pointers obtained via PyArena_Malloc() must never be passed to
* the system free() or realloc(), or to any of Python's similar memory-
* management functions. PyArena_Malloc()-obtained pointers remain valid
* until PyArena_Free(ar) is called, at which point all pointers obtained
* from the arena `ar` become invalid simultaneously.
PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);
/* This routine isn't a proper arena allocation routine. It takes
* a PyObject* and records it so that it can be DECREFed when the
* arena is freed.
PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);
#ifdef __cplusplus
#endif /* !Py_PYARENA_H */