Backport of:

------------------------------------------------------------
revno: 2630.4.10
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Mon 2008-05-26 15:11:26 +0400
message:
  WL#3726 "DDL locking for all metadata objects".

  After review changes in progress.
  Implemented some renames suggested by reviewer.


sql/mdl.cc:
  Renamed:
    MDL_LOCK_DATA::users -> lock_count
    MDL_LOCK_DATA::has_no_other_users() -> has_one_lock()
    MDL_LOCK::upgradable -> is_upgradable
    Moved variables used in global metadata lock implementation
    to separate strucuture.
sql/mdl.h:
  Renamed MDL_LOCK::upgradable to is_upgradable.

sql/mdl.h

@@ -66,7 +66,7 @@ struct MDL_LOCK
      point might be upgraded to an exclusive lock and therefore conflicts
      with global shared lock, FALSE -- otherwise.
   */
-  bool          upgradable;
+  bool          is_upgradable;
 
 private:
   /**
@@ -189,7 +189,7 @@ inline void mdl_set_lock_priority(MDL_LOCK *lock, enum_mdl_prio prio)
 inline void mdl_set_upgradable(MDL_LOCK *lock)
 {
   DBUG_ASSERT(lock->type == MDL_SHARED && lock->state == MDL_PENDING);
-  lock->upgradable= TRUE;
+  lock->is_upgradable= TRUE;
 }
 
 bool mdl_acquire_shared_lock(MDL_LOCK *l, bool *retry);