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1 /* An arena-like memory interface for the compiler.
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2 */
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3
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4 #ifndef Py_LIMITED_API
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5 #ifndef Py_PYARENA_H
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6 #define Py_PYARENA_H
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7
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8 #ifdef __cplusplus
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9 extern "C" {
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10 #endif
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11
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12 typedef struct _arena PyArena;
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13
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14 /* PyArena_New() and PyArena_Free() create a new arena and free it,
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15 respectively. Once an arena has been created, it can be used
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16 to allocate memory via PyArena_Malloc(). Pointers to PyObject can
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17 also be registered with the arena via PyArena_AddPyObject(), and the
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18 arena will ensure that the PyObjects stay alive at least until
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19 PyArena_Free() is called. When an arena is freed, all the memory it
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20 allocated is freed, the arena releases internal references to registered
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21 PyObject*, and none of its pointers are valid.
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22 XXX (tim) What does "none of its pointers are valid" mean? Does it
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23 XXX mean that pointers previously obtained via PyArena_Malloc() are
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24 XXX no longer valid? (That's clearly true, but not sure that's what
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25 XXX the text is trying to say.)
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26
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27 PyArena_New() returns an arena pointer. On error, it
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28 returns a negative number and sets an exception.
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29 XXX (tim): Not true. On error, PyArena_New() actually returns NULL,
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30 XXX and looks like it may or may not set an exception (e.g., if the
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31 XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on
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32 XXX and an exception is set; OTOH, if the internal
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33 XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but
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34 XXX an exception is not set in that case).
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35 */
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36 PyAPI_FUNC(PyArena *) PyArena_New(void);
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37 PyAPI_FUNC(void) PyArena_Free(PyArena *);
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38
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39 /* Mostly like malloc(), return the address of a block of memory spanning
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40 * `size` bytes, or return NULL (without setting an exception) if enough
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41 * new memory can't be obtained. Unlike malloc(0), PyArena_Malloc() with
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42 * size=0 does not guarantee to return a unique pointer (the pointer
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43 * returned may equal one or more other pointers obtained from
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44 * PyArena_Malloc()).
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45 * Note that pointers obtained via PyArena_Malloc() must never be passed to
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46 * the system free() or realloc(), or to any of Python's similar memory-
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47 * management functions. PyArena_Malloc()-obtained pointers remain valid
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48 * until PyArena_Free(ar) is called, at which point all pointers obtained
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49 * from the arena `ar` become invalid simultaneously.
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50 */
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51 PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);
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52
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53 /* This routine isn't a proper arena allocation routine. It takes
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54 * a PyObject* and records it so that it can be DECREFed when the
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55 * arena is freed.
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56 */
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57 PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);
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58
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59 #ifdef __cplusplus
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60 }
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61 #endif
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62
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63 #endif /* !Py_PYARENA_H */
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64 #endif /* Py_LIMITED_API */
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