Yet less TDC hash lookups

Let auto repair table and truncate table routines flush TABLE_SHARE
directly.

Part of MDEV-17882 - Cleanup refresh version

Author: svoj

sql/sql_base.cc

@@ -2942,9 +2942,7 @@ static bool auto_repair_table(THD *thd, TABLE_LIST *table_list)
     result= FALSE;
   }
 
-  tdc_release_share(share);
-  /* Remove the repaired share from the table cache. */
-  tdc_remove_table(thd, table_list->db.str, table_list->table_name.str);
+  tdc_remove_referenced_share(thd, share);
 end_free:
   my_free(entry);
   return result;

sql/sql_truncate.cc

@@ -336,7 +336,10 @@ bool Sql_cmd_truncate_table::lock_table(THD *thd, TABLE_LIST *table_ref,
     }
 #endif
 
-    tdc_release_share(share);
+    if (!versioned)
+      tdc_remove_referenced_share(thd, share);
+    else
+      tdc_release_share(share);
 
     if (hton == view_pseudo_hton)
     {
@@ -372,12 +375,6 @@ bool Sql_cmd_truncate_table::lock_table(THD *thd, TABLE_LIST *table_ref,
     if (*hton_can_recreate)
       close_all_tables_for_name(thd, table->s, HA_EXTRA_NOT_USED, NULL);
   }
-  else
-  {
-    /* Table is already locked exclusively. Remove cached instances. */
-    tdc_remove_table(thd, table_ref->db.str, table_ref->table_name.str);
-  }
-
   DBUG_RETURN(FALSE);
 }
 

sql/table_cache.cc

@@ -996,6 +996,20 @@ void tdc_release_share(TABLE_SHARE *share)
 }
 
 
+void tdc_remove_referenced_share(THD *thd, TABLE_SHARE *share)
+{
+  DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::TABLE, share->db.str,
+                                             share->table_name.str,
+                                             MDL_EXCLUSIVE));
+  share->tdc->flush_unused(false);
+  mysql_mutex_lock(&share->tdc->LOCK_table_share);
+  share->tdc->wait_for_refs(1);
+  DBUG_ASSERT(share->tdc->all_tables.is_empty());
+  share->tdc->ref_count--;
+  tdc_delete_share_from_hash(share->tdc);
+}
+
+
 /**
    Removes all TABLE instances and corresponding TABLE_SHARE
 
@@ -1009,7 +1023,6 @@ void tdc_release_share(TABLE_SHARE *share)
 
 void tdc_remove_table(THD *thd, const char *db, const char *table_name)
 {
-  Share_free_tables::List purge_tables;
   TDC_element *element;
   DBUG_ENTER("tdc_remove_table");
   DBUG_PRINT("enter", ("name: %s", table_name));
@@ -1042,18 +1055,10 @@ void tdc_remove_table(THD *thd, const char *db, const char *table_name)
   mysql_mutex_unlock(&LOCK_unused_shares);
 
   element->ref_count++;
-
-  tc_remove_all_unused_tables(element, &purge_tables);
   mysql_mutex_unlock(&element->LOCK_table_share);
 
-  while (auto table= purge_tables.pop_front())
-    intern_close_table(table);
-
-  mysql_mutex_lock(&element->LOCK_table_share);
-  element->wait_for_refs(1);
-  DBUG_ASSERT(element->all_tables.is_empty());
-  element->ref_count--;
-  tdc_delete_share_from_hash(element);
+  /* We have to relock the mutex to avoid code duplication. Sigh. */
+  tdc_remove_referenced_share(thd, element->share);
   DBUG_VOID_RETURN;
 }
 

sql/table_cache.h

@@ -77,6 +77,7 @@ int tdc_share_is_cached(THD *thd, const char *db, const char *table_name);
 extern TABLE_SHARE *tdc_acquire_share(THD *thd, TABLE_LIST *tl, uint flags,
                                       TABLE **out_table= 0);
 extern void tdc_release_share(TABLE_SHARE *share);
+void tdc_remove_referenced_share(THD *thd, TABLE_SHARE *share);
 void tdc_remove_table(THD *thd, const char *db, const char *table_name);
 
 extern int tdc_wait_for_old_version(THD *thd, const char *db,