WHAT: Simple patch that will fail an assert() if you OBJ_CONSTRUCT an object and its ref count goes to 0 (in debug builds only).
WHY: To catch bugs.
WHERE: opal/class/opal_class.h
WHEN: Timeout of 1 week -- COB, Thurs, 14 Mar, 2013
MORE DETAIL:
On the call on Tuesday, we talked about some ideas for catching bugs with respect to object reference counting. After the call, Brian, Ralph, and I came up with two useful asserts to help catch bugs (in debug builds only):
1. If you OBJ_CONSTRUCT an object, its ref count should never go to zero.
2. When a object is destroyed, its refcount should be exactly 1.
This RFC is for #1. The attached patch doesn't seem to cause any problems (and we didn't expect it to). But it's a good addition to the other asserts() that are already in the object code already.
As for #2, Ralph has previously found bugs in the ORTE layer that would have been much easier to track down if #2 were in place. I'll send an RFC for #2 when I have managed to fix all the problems that it has found in the OMPI layer... :-)
--
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
Index: opal/class/opal_object.h
===================================================================
--- opal/class/opal_object.h (revision 28147)
+++ opal/class/opal_object.h (working copy)
@@ -169,7 +169,7 @@
* @param NAME Name of the class to initialize
*/
#if OPAL_ENABLE_DEBUG
-#define OPAL_OBJ_STATIC_INIT(BASE_CLASS) { OPAL_OBJ_MAGIC_ID, OBJ_CLASS(BASE_CLASS), 1, __FILE__, __LINE__ }
+#define OPAL_OBJ_STATIC_INIT(BASE_CLASS) { OPAL_OBJ_MAGIC_ID, 1, OBJ_CLASS(BASE_CLASS), 1, __FILE__, __LINE__ }
#else
#define OPAL_OBJ_STATIC_INIT(BASE_CLASS) { OBJ_CLASS(BASE_CLASS), 1 }
#endif
@@ -184,6 +184,10 @@
/** Magic ID -- want this to be the very first item in the
struct's memory */
uint64_t obj_magic_id;
+ /* flag whether this was initialized using construct
+ * versus obj_new
+ */
+ bool constructed;
#endif
opal_class_t *obj_class; /**< class descriptor */
volatile int32_t obj_reference_count; /**< reference count */
@@ -252,6 +256,7 @@
object->obj_magic_id = OPAL_OBJ_MAGIC_ID;
object->cls_init_file_name = file;
object->cls_init_lineno = line;
+ object->constructed = false;
return object;
}
#define OBJ_NEW(type) \
@@ -313,6 +318,8 @@
assert(NULL != ((opal_object_t *) (object))->obj_class); \
assert(OPAL_OBJ_MAGIC_ID == ((opal_object_t *) (object))->obj_magic_id); \
if (0 == opal_obj_update((opal_object_t *) (object), -1)) { \
+ /* constructed objects are not allowed to reach 0 */ \
+ assert(!(((opal_object_t *) (object))->constructed)); \
OBJ_SET_MAGIC_ID((object), 0); \
opal_obj_run_destructors((opal_object_t *) (object)); \
OBJ_REMEMBER_FILE_AND_LINENO( object, __FILE__, __LINE__ ); \
@@ -344,6 +351,7 @@
OBJ_CONSTRUCT_INTERNAL((object), OBJ_CLASS(type)); \
} while (0)
+#if OPAL_ENABLE_DEBUG
#define OBJ_CONSTRUCT_INTERNAL(object, type) \
do { \
OBJ_SET_MAGIC_ID((object), OPAL_OBJ_MAGIC_ID); \
@@ -352,11 +360,24 @@
} \
((opal_object_t *) (object))->obj_class = (type); \
((opal_object_t *) (object))->obj_reference_count = 1; \
+ ((opal_object_t *) (object))->constructed = true; \
opal_obj_run_constructors((opal_object_t *) (object)); \
OBJ_REMEMBER_FILE_AND_LINENO( object, __FILE__, __LINE__ ); \
} while (0)
+#else
+#define OBJ_CONSTRUCT_INTERNAL(object, type) \
+do { \
+ OBJ_SET_MAGIC_ID((object), OPAL_OBJ_MAGIC_ID); \
+ if (0 == (type)->cls_initialized) { \
+ opal_class_initialize((type)); \
+ } \
+ ((opal_object_t *) (object))->obj_class = (type); \
+ ((opal_object_t *) (object))->obj_reference_count = 1; \
+ opal_obj_run_constructors((opal_object_t *) (object)); \
+ OBJ_REMEMBER_FILE_AND_LINENO( object, __FILE__, __LINE__ ); \
+} while (0)
+#endif
-
/**
* Destruct (finalize) an object that is not dynamically allocated.
*
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