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mdbx: drop lead_txnid(), g.e. undo tsan-aware changes.

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Change-Id: I18a86661b0bd58bf74c644c0ed96bd836afc040c
This commit is contained in:
Leo Yuriev 2016-03-13 19:30:59 +03:00
parent 14ddec2051
commit 1b7f1bc60a
1 changed files with 18 additions and 30 deletions
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48
mdb.c
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@ -2733,33 +2733,6 @@ mdb_reader_pid(MDB_env *env, int op, pid_t pid)
}
}
static
txnid_t lead_txnid(MDB_txn *txn, MDB_reader *r)
{
while(1) { /* LY: Retry on a race, ITS#7970. */
MDB_meta *meta = mdb_meta_head_r(txn->mt_env);
#ifdef __SANITIZE_THREAD__
pthread_mutex_lock(&tsan_mutex);
#endif
txnid_t lead = meta->mm_txnid;
r->mr_txnid = lead;
mdb_coherent_barrier();
/* Copy the DB info and flags */
memcpy(txn->mt_dbs, meta->mm_dbs, CORE_DBS * sizeof(MDB_db));
txn->mt_next_pgno = meta->mm_last_pg+1;
txnid_t snap = txn->mt_env->me_txns->mti_txnid;
#ifdef __SANITIZE_THREAD__
pthread_mutex_unlock(&tsan_mutex);
#endif
if (likely(lead == snap)) {
return lead;
}
#if defined(__i386__) || defined(__x86_64__)
__asm__ __volatile__("pause");
#endif
}
}
/** Common code for #mdb_txn_begin() and #mdb_txn_renew().
* @param[in] txn the transaction handle to initialize
* @return 0 on success, non-zero on failure.
@ -2769,7 +2742,6 @@ mdb_txn_renew0(MDB_txn *txn, unsigned flags)
{
MDB_env *env = txn->mt_env;
unsigned i, nr;
uint16_t x;
int rc, new_notls = 0;
if (unlikely(env->me_pid != getpid())) {
@ -2867,7 +2839,23 @@ mdb_txn_renew0(MDB_txn *txn, unsigned flags)
}
}
txn->mt_txnid = lead_txnid(txn, r);
while((env->me_flags & MDB_FATAL_ERROR) == 0) {
MDB_meta *meta = mdb_meta_head_r(txn->mt_env);
txnid_t lead = meta->mm_txnid;
r->mr_txnid = lead;
mdb_coherent_barrier();
txnid_t snap = txn->mt_env->me_txns->mti_txnid;
/* LY: Retry on a race, ITS#7970. */
if (likely(lead == snap)) {
txn->mt_txnid = lead;
txn->mt_next_pgno = meta->mm_last_pg+1;
/* Copy the DB info and flags */
memcpy(txn->mt_dbs, meta->mm_dbs, CORE_DBS * sizeof(MDB_db));
break;
}
}
txn->mt_u.reader = r;
txn->mt_dbxs = env->me_dbxs; /* mostly static anyway */
} else {
@ -2917,7 +2905,7 @@ mdb_txn_renew0(MDB_txn *txn, unsigned flags)
/* Setup db info */
txn->mt_numdbs = env->me_numdbs;
for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
x = env->me_dbflags[i];
unsigned x = env->me_dbflags[i];
txn->mt_dbs[i].md_flags = x & PERSISTENT_FLAGS;
txn->mt_dbflags[i] = (x & MDB_VALID) ? DB_VALID|DB_USRVALID|DB_STALE : 0;
}