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diff --git a/include/python2.7/pyarena.h b/include/python2.7/pyarena.h
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+/* An arena-like memory interface for the compiler.
+ */
+
+#ifndef Py_PYARENA_H
+#define Py_PYARENA_H
+
+#ifdef __cplusplus
+extern "C" {
+#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+ XXX no longer valid?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_PYARENA_H */