Revert "libmdb: Do not use the MDB_txbody.mtb_txnid field."

This reverts commit 4a0b30499caab8628efcedb8be5643fead7cd17e.

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 0c8e6aa0e5609092a37b90a95400474a24903b33..38825e948ec00838bc4797b12bf8714233249907 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -511,17 +511,11 @@ typedef struct MDB_txbody {
                 */
        pthread_mutex_t mtb_mutex;
 #endif
-#if MDB_VERSION == 1
                /**     The ID of the last transaction committed to the database.
                 *      This is recorded here only for convenience; the value can always
                 *      be determined by reading the main database meta pages.
-                *
-                *      Value is unused, but maintained for backwards compatibility.
-                *      Drop this or mtb_me_toggle when changing MDB_VERSION.
-                *      (Reading both should have been done atomically.)
                 */
        txnid_t         mtb_txnid;
-#endif
                /** The number of slots that have been used in the reader table.
                 *      This always records the maximum count, it is not decremented
                 *      when readers release their slots.
@@ -542,9 +536,7 @@ typedef struct MDB_txninfo {
 #define mti_version    mt1.mtb.mtb_version
 #define mti_mutex      mt1.mtb.mtb_mutex
 #define mti_rmname     mt1.mtb.mtb_rmname
-#if MDB_VERSION == 1
 #define mti_txnid      mt1.mtb.mtb_txnid
-#endif
 #define mti_numreaders mt1.mtb.mtb_numreaders
 #define mti_me_toggle  mt1.mtb.mtb_me_toggle
                char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
@@ -1584,19 +1576,18 @@ mdb_txn_renew0(MDB_txn *txn)
                        pthread_setspecific(env->me_txkey, r);
                }
                txn->mt_toggle = env->me_txns->mti_me_toggle;
-               txn->mt_txnid = r->mr_txnid = env->me_metas[txn->mt_toggle]->mm_txnid;
-
+               txn->mt_txnid = env->me_txns->mti_txnid;
                /* This happens if a different process was the
                 * last writer to the DB.
                 */
                if (env->me_wtxnid < txn->mt_txnid)
                        mt_dbflag = DB_STALE;
+               r->mr_txnid = txn->mt_txnid;
                txn->mt_u.reader = r;
        } else {
                LOCK_MUTEX_W(env);
 
-               txn->mt_toggle = env->me_txns->mti_me_toggle;
-               txn->mt_txnid = env->me_metas[txn->mt_toggle]->mm_txnid;
+               txn->mt_txnid = env->me_txns->mti_txnid;
                if (env->me_wtxnid < txn->mt_txnid)
                        mt_dbflag = DB_STALE;
                txn->mt_txnid++;
@@ -1604,6 +1595,7 @@ mdb_txn_renew0(MDB_txn *txn)
                if (txn->mt_txnid == mdb_debug_start)
                        mdb_debug = 1;
 #endif
+               txn->mt_toggle = env->me_txns->mti_me_toggle;
                txn->mt_u.dirty_list = env->me_dirty_list;
                txn->mt_u.dirty_list[0].mid = 0;
                txn->mt_free_pgs = env->me_free_pgs;