[Python-checkins] r43489 - python/trunk/Python/pyarena.c

Fri Mar 31 18:41:23 CEST 2006

Author: jeremy.hylton
Date: Fri Mar 31 18:41:22 2006
New Revision: 43489
Modified:
 python/trunk/Python/pyarena.c
Log:
Expand comments.
Explicitly clear all elements from arena->a_objects and remove
assert() that refcount is 1. It's possible for a program to get a
reference to the list via sys.getobjects() or via gc functions.
Modified: python/trunk/Python/pyarena.c
==============================================================================

--- python/trunk/Python/pyarena.c	(original)
+++ python/trunk/Python/pyarena.c	Fri Mar 31 18:41:22 2006
@@ -6,6 +6,9 @@
 Measurements with standard library modules suggest the average
 allocation is about 20 bytes and that most compiles use a single
 block.
+
+ TODO(jhylton): Think about a realloc API, maybe just for the last
+ allocation?
 */
 
 #define DEFAULT_BLOCK_SIZE 8192
@@ -39,9 +42,25 @@
 */
 
 struct _arena {
+ /* Pointer to the first block allocated for the arena, never NULL.
+ It is used only to find the first block when the arena is
+ being freed.
+ */
 	block *a_head;
+
+ /* Pointer to the block currently used for allocation. It's
+ ab_next field should be NULL. If it is not-null after a
+ call to block_alloc(), it means a new block has been allocated
+ and a_cur should be reset to point it.
+ */
 	block *a_cur;
+
+ /* A Python list object containing references to all the PyObject
+ pointers associated with this area. They will be DECREFed
+ when the arena is freed.
+ */
 PyObject *a_objects;
+
 #if defined(Py_DEBUG)
 /* Debug output */
 size_t total_allocs;
@@ -134,6 +153,7 @@
 void
 PyArena_Free(PyArena *arena)
 {
+ int r;
 	assert(arena);
 #if defined(Py_DEBUG)
 /*
@@ -146,6 +166,13 @@
 #endif
 	block_free(arena->a_head);
 assert(arena->a_objects->ob_refcnt == 1);
+
+ /* Clear all the elements from the list. This is necessary
+ to guarantee that they will be DECREFed. */
+ r = PyList_SetSlice(arena->a_objects,
+ 0, PyList_GET_SIZE(arena->a_objects), NULL);
+ assert(r == 0);
+ assert(PyList_GET_SIZE(arena->a_objects) == 0);
 Py_DECREF(arena->a_objects);
 	free(arena);
 }
