ITS#8156 Fix MDB_MAXKEYSIZE doc

[openldap] / libraries / liblmdb / mdb.c

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 86635bfea63fe80b1437c266261780fe7bf74186..6bdf3151dcca23220157c1efa3caa2f562e61374 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -446,12 +446,17 @@ static txnid_t mdb_debug_start;
        /**     The version number for a database's lockfile format. */
 #define MDB_LOCK_VERSION        1
 
-       /**     @brief The max size of a key we can write, or 0 for dynamic max.
+       /**     @brief The max size of a key we can write, or 0 for computed max.
         *
-        *      Define this as 0 to compute the max from the page size.  511
-        *      is default for backwards compat: liblmdb <= 0.9.10 can break
-        *      when modifying a DB with keys/dupsort data bigger than its max.
-        *      #MDB_DEVEL sets the default to 0.
+        *      This macro should normally be left alone or set to 0.
+        *      Note that a database with big keys or dupsort data cannot be
+        *      reliably modified by a liblmdb which uses a smaller max.
+        *      The default is 511 for backwards compat, or 0 when #MDB_DEVEL.
+        *
+        *      Other values are allowed, for backwards compat.  However:
+        *      A value bigger than the computed max can break if you do not
+        *      know what you are doing, and liblmdb <= 0.9.10 can break when
+        *      modifying a DB with keys/dupsort data bigger than its max.
         *
         *      Data items in an #MDB_DUPSORT database are also limited to
         *      this size, since they're actually keys of a sub-DB.  Keys and
@@ -2498,15 +2503,11 @@ mdb_txn_renew0(MDB_txn *txn)
        MDB_env *env = txn->mt_env;
        MDB_txninfo *ti = env->me_txns;
        MDB_meta *meta;
-       unsigned int i, nr;
+       unsigned int i, nr, flags = txn->mt_flags;
        uint16_t x;
        int rc, new_notls = 0;
 
-       if (txn->mt_flags & MDB_TXN_RDONLY) {
-               txn->mt_flags = MDB_TXN_RDONLY;
-               /* Setup db info */
-               txn->mt_numdbs = env->me_numdbs;
-               txn->mt_dbxs = env->me_dbxs;    /* mostly static anyway */
+       if ((flags &= MDB_TXN_RDONLY) != 0) {
                if (!ti) {
                        meta = env->me_metas[ mdb_env_pick_meta(env) ];
                        txn->mt_txnid = meta->mm_txnid;
@@ -2559,6 +2560,7 @@ mdb_txn_renew0(MDB_txn *txn)
                        txn->mt_u.reader = r;
                        meta = env->me_metas[txn->mt_txnid & 1];
                }
+               txn->mt_dbxs = env->me_dbxs;    /* mostly static anyway */
        } else {
                if (ti) {
                        LOCK_MUTEX_W(env);
@@ -2569,14 +2571,11 @@ mdb_txn_renew0(MDB_txn *txn)
                        meta = env->me_metas[ mdb_env_pick_meta(env) ];
                        txn->mt_txnid = meta->mm_txnid;
                }
-               /* Setup db info */
-               txn->mt_numdbs = env->me_numdbs;
                txn->mt_txnid++;
 #if MDB_DEBUG
                if (txn->mt_txnid == mdb_debug_start)
                        mdb_debug = 1;
 #endif
-               txn->mt_flags = 0;
                txn->mt_child = NULL;
                txn->mt_loose_pgs = NULL;
                txn->mt_loose_count = 0;
@@ -2596,6 +2595,10 @@ mdb_txn_renew0(MDB_txn *txn)
        /* Moved to here to avoid a data race in read TXNs */
        txn->mt_next_pgno = meta->mm_last_pg+1;
 
+       txn->mt_flags = flags;
+
+       /* Setup db info */
+       txn->mt_numdbs = env->me_numdbs;
        for (i=2; i<txn->mt_numdbs; i++) {
                x = env->me_dbflags[i];
                txn->mt_dbs[i].md_flags = x & PERSISTENT_FLAGS;