mdb_txn_renew0(): Fix un-mutexed me_flags update.

Replace env flag MDB_LIVE_READER with field me_live_reader.

diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h
index 794269e218fa49905245d4fa12e2ed63533394ad..62f0a485dea8ec15a1ff4fa94487eb84d0296536 100644 (file)
--- a/libraries/liblmdb/lmdb.h
+++ b/libraries/liblmdb/lmdb.h
@@ -668,7 +668,8 @@ void mdb_env_close(MDB_env *env);
        /** @brief Set environment flags.
         *
         * This may be used to set some flags in addition to those from
-        * #mdb_env_open(), or to unset these flags.
+        * #mdb_env_open(), or to unset these flags.  If several threads
+        * change the flags at the same time, the result is undefined.
         * @param[in] env An environment handle returned by #mdb_env_create()
         * @param[in] flags The flags to change, bitwise OR'ed together
         * @param[in] onoff A non-zero value sets the flags, zero clears them.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 03ad2cc3fe848f23b8e2dd8ae782f2c4c252a1fc..a3ac603f882f58cd01dad1807c35f7381c344b45 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -1034,8 +1034,6 @@ struct MDB_env {
 #define        MDB_ENV_ACTIVE  0x20000000U
        /** me_txkey is set */
 #define        MDB_ENV_TXKEY   0x10000000U
-       /** Have liveness lock in reader table */
-#define        MDB_LIVE_READER 0x08000000U
        uint32_t        me_flags;               /**< @ref mdb_env */
        unsigned int    me_psize;       /**< DB page size, inited from me_os_psize */
        unsigned int    me_os_psize;    /**< OS page size, from #GET_PAGESIZE */
@@ -1071,6 +1069,7 @@ struct MDB_env {
 #if !(MDB_MAXKEYSIZE)
        unsigned int    me_maxkey;      /**< max size of a key */
 #endif
+       int             me_live_reader;         /**< have liveness lock in reader table */
 #ifdef _WIN32
        int             me_pidquery;            /**< Used in OpenProcess */
        HANDLE          me_rmutex;              /* Windows mutexes don't reside in shared mem */
@@ -2268,11 +2267,11 @@ mdb_txn_renew0(MDB_txn *txn)
                                MDB_PID_T pid = env->me_pid;
                                pthread_t tid = pthread_self();
 
-                               if (!(env->me_flags & MDB_LIVE_READER)) {
+                               if (!env->me_live_reader) {
                                        rc = mdb_reader_pid(env, Pidset, pid);
                                        if (rc)
                                                return rc;
-                                       env->me_flags |= MDB_LIVE_READER;
+                                       env->me_live_reader = 1;
                                }
 
                                LOCK_MUTEX_R(env);