Applied all changes from Igor and Sanja

1 files changed, 15 insertions, 4 deletions

diff --git a/sql/mdl.h b/sql/mdl.h
index c778dbbc1d7..82d764bc66c 100644
--- a/sql/mdl.h
+++ b/sql/mdl.h
@@ -132,6 +132,15 @@ enum enum_mdl_type {
   */
   MDL_SHARED_WRITE,
   /*
+    An upgradable shared metadata lock for cases when there is an intention
+    to modify (and not just read) data in the table.
+    Can be upgraded to MDL_SHARED_NO_WRITE and MDL_EXCLUSIVE.
+    A connection holding SU lock can read table metadata and modify or read
+    table data (after acquiring appropriate table and row-level locks).
+    To be used for the first phase of ALTER TABLE.
+  */
+  MDL_SHARED_UPGRADABLE,
+  /*
     An upgradable shared metadata lock which blocks all attempts to update
     table data, allowing reads.
     A connection holding this kind of lock can read table metadata and read
@@ -502,13 +511,14 @@ public:
   MDL_context *get_ctx() const { return m_ctx; }
   bool is_upgradable_or_exclusive() const
   {
-    return m_type == MDL_SHARED_NO_WRITE ||
+    return m_type == MDL_SHARED_UPGRADABLE ||
+           m_type == MDL_SHARED_NO_WRITE ||
            m_type == MDL_SHARED_NO_READ_WRITE ||
            m_type == MDL_EXCLUSIVE;
   }
   enum_mdl_type get_type() const { return m_type; }
   MDL_lock *get_lock() const { return m_lock; }
-  void downgrade_exclusive_lock(enum_mdl_type type);
+  void downgrade_lock(enum_mdl_type type);
 
   bool has_stronger_or_equal_type(enum_mdl_type type) const;
 
@@ -660,8 +670,9 @@ public:
   bool try_acquire_lock(MDL_request *mdl_request);
   bool acquire_lock(MDL_request *mdl_request, ulong lock_wait_timeout);
   bool acquire_locks(MDL_request_list *requests, ulong lock_wait_timeout);
-  bool upgrade_shared_lock_to_exclusive(MDL_ticket *mdl_ticket,
-                                        ulong lock_wait_timeout);
+  bool upgrade_shared_lock(MDL_ticket *mdl_ticket,
+                           enum_mdl_type new_type,
+                           ulong lock_wait_timeout);
 
   bool clone_ticket(MDL_request *mdl_request);