1 files changed, 24 insertions, 10 deletions

diff --git a/sql/mdl.cc b/sql/mdl.cc
index d53ddcee0c8..aa7c2a4b7f2 100644
--- a/sql/mdl.cc
+++ b/sql/mdl.cc
@@ -124,7 +124,6 @@ public:
   Deadlock_detection_visitor(MDL_context *start_node_arg)
     : m_start_node(start_node_arg),
       m_victim(NULL),
-      m_current_search_depth(0),
       m_found_deadlock(FALSE)
   {}
   virtual bool enter_node(MDL_context *node);
@@ -133,6 +132,8 @@ public:
   virtual bool inspect_edge(MDL_context *dest);
 
   MDL_context *get_victim() const { return m_victim; }
+
+  void abort_traversal(MDL_context *node);
 private:
   /**
     Change the deadlock victim to a new one if it has lower deadlock
@@ -147,13 +148,6 @@ private:
   MDL_context *m_start_node;
   /** If a deadlock is found, the context that identifies the victim. */
   MDL_context *m_victim;
-  /** Set to the 0 at start. Increased whenever
-    we descend into another MDL context (aka traverse to the next
-    wait-for graph node). When MAX_SEARCH_DEPTH is reached, we
-    assume that a deadlock is found, even if we have not found a
-    loop.
-  */
-  uint m_current_search_depth;
   /** TRUE if we found a deadlock. */
   bool m_found_deadlock;
   /**
@@ -187,7 +181,7 @@ private:
 
 bool Deadlock_detection_visitor::enter_node(MDL_context *node)
 {
-  m_found_deadlock= ++m_current_search_depth >= MAX_SEARCH_DEPTH;
+  m_found_deadlock= m_current_search_depth >= MAX_SEARCH_DEPTH;
   if (m_found_deadlock)
   {
     DBUG_ASSERT(! m_victim);
@@ -207,7 +201,6 @@ bool Deadlock_detection_visitor::enter_node(MDL_context *node)
 
 void Deadlock_detection_visitor::leave_node(MDL_context *node)
 {
-  --m_current_search_depth;
   if (m_found_deadlock)
     opt_change_victim_to(node);
 }
@@ -252,6 +245,21 @@ Deadlock_detection_visitor::opt_change_victim_to(MDL_context *new_victim)
 
 
 /**
+  Abort traversal of a wait-for graph and report a deadlock.
+
+  @param node Node which we were about to visit when abort
+              was initiated.
+*/
+
+void Deadlock_detection_visitor::abort_traversal(MDL_context *node)
+{
+  DBUG_ASSERT(! m_victim);
+  m_found_deadlock= TRUE;
+  opt_change_victim_to(node);
+}
+
+
+/**
   Get a bit corresponding to enum_mdl_type value in a granted/waiting bitmaps
   and compatibility matrices.
 */
@@ -2056,8 +2064,13 @@ bool MDL_lock::visit_subgraph(MDL_ticket *waiting_ticket,
     are visiting it but this is OK: in the worst case we might do some
     extra work and one more context might be chosen as a victim.
   */
+  ++gvisitor->m_current_search_depth;
+
   if (gvisitor->enter_node(src_ctx))
+  {
+    --gvisitor->m_current_search_depth;
     goto end;
+  }
 
   /*
     We do a breadth-first search first -- that is, inspect all
@@ -2114,6 +2127,7 @@ bool MDL_lock::visit_subgraph(MDL_ticket *waiting_ticket,
 
 end_leave_node:
   gvisitor->leave_node(src_ctx);
+  --gvisitor->m_current_search_depth;
 
 end:
   mysql_prlock_unlock(&m_rwlock);