MDEV-5864 - Reduce usage of LOCK_open: TABLE_SHARE::tdc.free_tables

Let TABLE_SHARE::tdc.free_tables, TABLE_SHARE::tdc.all_tables,
TABLE_SHARE::tdc.flushed and corresponding invariants be protected by
per-share TABLE_SHARE::tdc.LOCK_table_share instead of global LOCK_open.

1 files changed, 1 insertions, 15 deletions

diff --git a/sql/mdl.h b/sql/mdl.h
index 6f31b46f17f..dbd44e8c6ab 100644
--- a/sql/mdl.h
+++ b/sql/mdl.h
@@ -519,17 +519,7 @@ public:
 
   virtual bool inspect_edge(MDL_context *dest) = 0;
   virtual ~MDL_wait_for_graph_visitor();
-  MDL_wait_for_graph_visitor() :m_lock_open_count(0) {}
-public:
-  /**
-   XXX, hack: During deadlock search, we may need to
-   inspect TABLE_SHAREs and acquire LOCK_open. Since
-   LOCK_open is not a recursive mutex, count here how many
-   times we "took" it (but only take and release once).
-   Not using a native recursive mutex or rwlock in 5.5 for
-   LOCK_open since it has significant performance impacts.
-  */
-  uint m_lock_open_count;
+  MDL_wait_for_graph_visitor() {}
 };
 
 /**
@@ -980,10 +970,6 @@ extern "C" unsigned long thd_get_thread_id(const MYSQL_THD thd);
 */
 extern "C" int thd_is_connected(MYSQL_THD thd);
 
-#ifndef DBUG_OFF
-extern mysql_mutex_t LOCK_open;
-#endif
-
 
 /*
   Start-up parameter for the maximum size of the unused MDL_lock objects cache