MDEV-6089 - MySQL WL#7305 "Improve MDL scalability by using lock-free hash"

Replaced hash with lock-free hash.

mysql-test/r/create_or_replace.result

@@ -264,8 +264,8 @@ select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	mysqltest2	
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	mysqltest2	t2
 create or replace table test.t1;
 ERROR 42000: A table must have at least 1 column
@@ -291,8 +291,8 @@ select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	mysqltest2	
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	mysqltest2	t2
 create or replace table test.t1 (a int) select 1 as 'a', 2 as 'a';
 ERROR 42S21: Duplicate column name 'a'
@@ -400,29 +400,29 @@ select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_SHARED_READ	MDL_EXPLICIT	Table metadata lock	test	t2
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 create or replace table t1 (i int);
 select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_SHARED_READ	MDL_EXPLICIT	Table metadata lock	test	t2
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 create or replace table t1 like t2;
 select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_SHARED_READ	MDL_EXPLICIT	Table metadata lock	test	t2
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 create or replace table t1 select 1 as f1;
 select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 #	MDL_SHARED_READ	MDL_EXPLICIT	Table metadata lock	test	t2
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
 drop table t1;
 unlock tables;
 #

sql/mdl.h

@@ -28,7 +28,7 @@
 #include <my_sys.h>
 #include <m_string.h>
 #include <mysql_com.h>
-#include <hash.h>
+#include <lf.h>
 
 #include <algorithm>
 
@@ -917,6 +917,7 @@ class MDL_context
     readily available to the wait-for graph iterator.
    */
   MDL_wait_for_subgraph *m_waiting_for;
+  LF_PINS *m_pins;
 private:
   MDL_ticket *find_ticket(MDL_request *mdl_req,
                           enum_mdl_duration *duration);
@@ -924,6 +925,7 @@ class MDL_context
   void release_lock(enum_mdl_duration duration, MDL_ticket *ticket);
   bool try_acquire_lock_impl(MDL_request *mdl_request,
                              MDL_ticket **out_ticket);
+  bool fix_pins();
 
 public:
   THD *get_thd() const { return m_owner->get_thd(); }