Edit: pycore_pyarena.h
/* An arena-like memory interface for the compiler. */ #ifndef Py_INTERNAL_PYARENA_H #define Py_INTERNAL_PYARENA_H #ifdef __cplusplus extern "C" { #endif #ifndef Py_BUILD_CORE # error "this header requires Py_BUILD_CORE define" #endif 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 Does it XXX mean that pointers previously obtained via _PyArena_Malloc() are XXX no longer valid?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 #endif /* !Py_INTERNAL_PYARENA_H */
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