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23 XXX no longer valid?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