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Fix data race in disclaim_weakmap_test statistic counters update

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(fix of commit 6eba4218a)

Issue #239 (bdwgc).

The stat_* variables need to be atomically updated, since the locking
of the map is granular (cf WEAKMAP_MUTEX_COUNT) to allow parallelism
between different key hashes.

* tests/disclaim_weakmap_test.c [!AO_CLEAR] (AO_t): Define.
* tests/disclaim_weakmap_test.c [!AO_HAVE_fetch_and_add1]
(AO_fetch_and_add1): Define.
* tests/disclaim_weakmap_test.c (stat_added, stat_found, stat_removed,
stat_skip_marked, stat_skip_locked): Change type back from unsigned to
volatile AO_t.
* tests/disclaim_weakmap_test.c (weakmap_add, weakmap_disclaim):
Update stat_* counters using AO_fetch_and_add1(); move counters update
outside weakmap_lock/unlock block.
* tests/disclaim_weakmap_test.c (main): Cast stat_* counters to
unsigned type in printf() call.
This commit is contained in:
Ivan Maidanski
2018-10-30 10:38:56 +03:00
parent 548ac4fbc6
commit 95e0747277
1 changed files with 24 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tests/disclaim_weakmap_test.c
+24 -22
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@@ -85,6 +85,16 @@
} \
} while (0)
/* Define AO primitives in case of no threads support. */
#ifndef AO_CLEAR
/* AO_t not defined. */
# define AO_t GC_word
#endif
#ifndef AO_HAVE_fetch_and_add1
# define AO_fetch_and_add1(p) ((*(p))++)
/* This is used only to update counters. */
#endif
unsigned memhash(void *src, size_t len)
{
unsigned acc = 0;
@@ -97,16 +107,11 @@ unsigned memhash(void *src, size_t len)
return acc;
}
static unsigned stat_added;
static unsigned stat_found;
static unsigned stat_removed;
static unsigned stat_skip_marked;
#ifdef AO_HAVE_fetch_and_add1
static volatile AO_t stat_skip_locked;
#else
static unsigned stat_skip_locked;
#endif
static volatile AO_t stat_added;
static volatile AO_t stat_found;
static volatile AO_t stat_removed;
static volatile AO_t stat_skip_locked;
static volatile AO_t stat_skip_marked;
struct weakmap_link {
GC_hidden_pointer obj;
@@ -192,8 +197,8 @@ void *weakmap_add(struct weakmap *wm, void *obj)
wm->obj_size - key_size);
GC_end_stubborn_change((char *)old_obj + key_size);
}
++stat_found;
weakmap_unlock(wm, h);
AO_fetch_and_add1(&stat_found);
# ifdef DEBUG_DISCLAIM_WEAKMAP
printf("Found %p, hash=%p\n", old_obj, (void *)(GC_word)h);
# endif
@@ -217,8 +222,8 @@ void *weakmap_add(struct weakmap *wm, void *obj)
new_link->next = *first;
GC_END_STUBBORN_CHANGE(new_link);
GC_PTR_STORE_AND_DIRTY(first, new_link);
++stat_added;
weakmap_unlock(wm, h);
AO_fetch_and_add1(&stat_added);
# ifdef DEBUG_DISCLAIM_WEAKMAP
printf("Added %p, hash=%p\n", new_obj, (void *)(GC_word)h);
# endif
@@ -245,30 +250,26 @@ int GC_CALLBACK weakmap_disclaim(void *obj_base)
/* Lock and check for mark. */
h = memhash(obj, wm->key_size);
if (weakmap_trylock(wm, h) != 0) {
# ifdef AO_HAVE_fetch_and_add1
AO_fetch_and_add1(&stat_skip_locked);
# else
++stat_skip_locked;
# endif
AO_fetch_and_add1(&stat_skip_locked);
# ifdef DEBUG_DISCLAIM_WEAKMAP
printf("Skipping locked %p, hash=%p\n", obj, (void *)(GC_word)h);
# endif
return 1;
}
if (GC_is_marked(obj_base)) {
weakmap_unlock(wm, h);
AO_fetch_and_add1(&stat_skip_marked);
# ifdef DEBUG_DISCLAIM_WEAKMAP
printf("Skipping marked %p, hash=%p\n", obj, (void *)(GC_word)h);
# endif
++stat_skip_marked;
weakmap_unlock(wm, h);
return 1;
}
/* Remove obj from wm. */
AO_fetch_and_add1(&stat_removed);
# ifdef DEBUG_DISCLAIM_WEAKMAP
printf("Removing %p, hash=%p\n", obj, (void *)(GC_word)h);
# endif
++stat_removed;
*(GC_word *)obj_base |= INVALIDATE_FLAG;
for (link = &wm->links[h % wm->capacity];; link = &(*link)->next) {
void *old_obj;
@@ -462,7 +463,8 @@ int main(void)
# endif
weakmap_destroy(pair_hcset);
printf("%u added, %u found; %u removed, %u locked, %u marked; %u remains\n",
stat_added, stat_found, stat_removed, (unsigned)stat_skip_locked,
stat_skip_marked, stat_added - stat_removed);
(unsigned)stat_added, (unsigned)stat_found, (unsigned)stat_removed,
(unsigned)stat_skip_locked, (unsigned)stat_skip_marked,
(unsigned)stat_added - (unsigned)stat_removed);
return 0;
}