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mdbx: avoid tsan-trap in mdb_meta_head_r().

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Change-Id: I594c13e1fe908f8afdc663d349cfc4cf634bba77
This commit is contained in:
Leo Yuriev 2015-12-06 13:37:45 +03:00
parent 5bc0a76899
commit 4e5d5ef935
1 changed files with 11 additions and 6 deletions
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15
mdb.c
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@ -1857,17 +1857,18 @@ static MDB_meta* mdb_meta_head_w(MDB_env *env) {
return a;
}
static MDB_meta* mdb_meta_head_r(MDB_env *env) {
static ATTRIBUTE_NO_SANITIZE_THREAD /* LY: avoid tsan-trap by meta->mm_txnid */
MDB_meta* mdb_meta_head_r(MDB_env *env) {
MDB_meta* a = METAPAGE_1(env);
MDB_meta* b = METAPAGE_2(env), *h;
txnid_t head_txnid;
int loop = 0, rc;
do {
while(1) {
head_txnid = env->me_txns->mti_txnid;
mdb_assert(env, a->mm_txnid != b->mm_txnid || head_txnid == 0);
if (a->mm_txnid == head_txnid)
if (likely(a->mm_txnid == head_txnid))
return a;
if (likely(b->mm_txnid == head_txnid))
return b;
@ -1877,9 +1878,13 @@ static MDB_meta* mdb_meta_head_r(MDB_env *env) {
__asm__ __volatile__("pause");
#endif
mdb_coherent_barrier();
if (loop > 2)
loop += 1;
if(likely(loop < 3))
continue;
if(unlikely(loop > 5))
break;
pthread_yield();
} while (++loop < 5);
}
rc = mdb_mutex_lock(env, MDB_MUTEX(env, w));
h = mdb_meta_head_w(env);