/* An arena-like memory interface for the compiler.

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*/

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#ifndef Py_LIMITED_API

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#ifndef Py_PYARENA_H

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#define Py_PYARENA_H

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#ifdef __cplusplus

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extern "C" {

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#endif

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typedef struct _arena PyArena;

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/* PyArena_New() and PyArena_Free() create a new arena and free it,

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respectively. Once an arena has been created, it can be used

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to allocate memory via PyArena_Malloc(). Pointers to PyObject can

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also be registered with the arena via PyArena_AddPyObject(), and the

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arena will ensure that the PyObjects stay alive at least until

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PyArena_Free() is called. When an arena is freed, all the memory it

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allocated is freed, the arena releases internal references to registered

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PyObject*, and none of its pointers are valid.

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XXX (tim) What does "none of its pointers are valid" mean? Does it

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XXX mean that pointers previously obtained via PyArena_Malloc() are

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XXX no longer valid? (That's clearly true, but not sure that's what

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XXX the text is trying to say.)

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PyArena_New() returns an arena pointer. On error, it

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returns a negative number and sets an exception.

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XXX (tim): Not true. On error, PyArena_New() actually returns NULL,

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XXX and looks like it may or may not set an exception (e.g., if the

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XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on

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XXX and an exception is set; OTOH, if the internal

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XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but

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XXX an exception is not set in that case).

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*/

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PyAPI_FUNC(PyArena *) PyArena_New(void);

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PyAPI_FUNC(void) PyArena_Free(PyArena *);

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/* Mostly like malloc(), return the address of a block of memory spanning

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* `size` bytes, or return NULL (without setting an exception) if enough

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* new memory can't be obtained. Unlike malloc(0), PyArena_Malloc() with

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* size=0 does not guarantee to return a unique pointer (the pointer

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* returned may equal one or more other pointers obtained from

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* PyArena_Malloc()).

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* Note that pointers obtained via PyArena_Malloc() must never be passed to

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* the system free() or realloc(), or to any of Python's similar memory-

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* management functions. PyArena_Malloc()-obtained pointers remain valid

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* until PyArena_Free(ar) is called, at which point all pointers obtained

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* from the arena `ar` become invalid simultaneously.

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*/

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PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);

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/* This routine isn't a proper arena allocation routine. It takes

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* a PyObject* and records it so that it can be DECREFed when the

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* arena is freed.

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*/

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PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);

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#ifdef __cplusplus

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}

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#endif

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#endif /* !Py_PYARENA_H */

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#endif /* Py_LIMITED_API */

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