Prelock child tables in addition to parent ones

4 files changed, 54 insertions, 37 deletions

diff --git a/mysql-test/suite/innodb/r/truncate_foreign.result b/mysql-test/suite/innodb/r/truncate_foreign.result
index bcf5b16aa83..55e8b6b44be 100644
--- a/mysql-test/suite/innodb/r/truncate_foreign.result
+++ b/mysql-test/suite/innodb/r/truncate_foreign.result
@@ -33,6 +33,7 @@ TRUNCATE TABLE child;
 ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 SET DEBUG_SYNC='now SIGNAL go';
 connection dml;
+# Truncate will not start until delete will release prelocked child
 ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `child_ibfk_1` FOREIGN KEY (`a`) REFERENCES `parent` (`a`) ON UPDATE CASCADE)
 SELECT * FROM child;
 a
@@ -44,14 +45,18 @@ connection default;
 SET DEBUG_SYNC='now WAIT_FOR fk';
 SET foreign_key_checks=0;
 TRUNCATE TABLE parent;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 SET DEBUG_SYNC='now SIGNAL go';
 connection dml;
-ERROR 23000: Cannot add or update a child row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `child_ibfk_1` FOREIGN KEY (`a`) REFERENCES `parent` (`a`) ON UPDATE CASCADE)
+# The row will be successfully inserted before truncation during prelocking
 SELECT * FROM parent;
 a
+3
+5
 SELECT * FROM child;
 a
 3
+5
 disconnect dml;
 connection default;
 SET DEBUG_SYNC = RESET;
diff --git a/mysql-test/suite/innodb/t/truncate_foreign.test b/mysql-test/suite/innodb/t/truncate_foreign.test
index 2c00c0641e9..b185d836b3a 100644
--- a/mysql-test/suite/innodb/t/truncate_foreign.test
+++ b/mysql-test/suite/innodb/t/truncate_foreign.test
@@ -42,6 +42,7 @@ TRUNCATE TABLE child;
 SET DEBUG_SYNC='now SIGNAL go';
 
 connection dml;
+--echo # Truncate will not start until delete will release prelocked child
 --error ER_ROW_IS_REFERENCED_2
 reap;
 SELECT * FROM child;
@@ -52,11 +53,12 @@ send INSERT INTO child SET a=5;
 connection default;
 SET DEBUG_SYNC='now WAIT_FOR fk';
 SET foreign_key_checks=0;
+--error ER_LOCK_WAIT_TIMEOUT
 TRUNCATE TABLE parent;
 SET DEBUG_SYNC='now SIGNAL go';
 
 connection dml;
---error ER_NO_REFERENCED_ROW_2
+--echo # The row will be successfully inserted before truncation during prelocking
 reap;
 SELECT * FROM parent;
 SELECT * FROM child;
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 766c5ec0d04..64434acd9e7 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -4625,6 +4625,41 @@ add_internal_tables(THD *thd, Query_tables_list *prelocking_ctx,
   DBUG_RETURN(FALSE);
 }
 
+static
+void prelock_fk_tables(THD *thd, TABLE_LIST *table_list,
+                       Query_tables_list *prelocking_ctx,
+                       List<FOREIGN_KEY_INFO> &fk_list,
+                       bool is_foreign)
+{
+  for (auto fk: fk_list)
+  {
+    uint8 op= table_list->trg_event_map;
+    bool del_modifies_child= fk_modifies_child(fk.delete_method);
+    bool upd_modifiels_child= fk_modifies_child(fk.update_method);
+
+    thr_lock_type lock_type= TL_READ;
+    if (!is_foreign
+        && ((op & (1u << TRG_EVENT_DELETE) && del_modifies_child)
+            || (op & (1u << TRG_EVENT_UPDATE) && upd_modifiels_child)))
+      lock_type= TL_WRITE_ALLOW_WRITE;
+
+    auto *db= is_foreign ? fk.referenced_db : fk.foreign_db;
+    auto *table_name= is_foreign ? fk.referenced_table : fk.foreign_table;
+
+    if (table_already_fk_prelocked(prelocking_ctx->query_tables,
+                                   db, table_name, lock_type))
+      continue;
+
+    TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));
+    tl->init_one_table_for_prelocking(db, table_name,
+                                      NULL, lock_type,
+                                      TABLE_LIST::PRELOCK_FK,
+                                      table_list->belong_to_view,
+                                      table_list->trg_event_map,
+                                      &prelocking_ctx->query_tables_last,
+                                      table_list->for_insert_data);
+  }
+}
 
 
 /**
@@ -4670,43 +4705,14 @@ handle_table(THD *thd, Query_tables_list *prelocking_ctx,
         return TRUE;
     }
 
-    if (table->s->referenced_by_foreign_key())
+    if (table->s->referenced_by_foreign_key() || table->s->has_foreign_keys())
     {
-      List_iterator<FOREIGN_KEY_INFO> fk_list_it(table->s->referenced_keys);
-      FOREIGN_KEY_INFO *fk;
-      Query_arena *arena, backup;
-
-      arena= thd->activate_stmt_arena_if_needed(&backup);
       *need_prelocking= TRUE;
-
-      while ((fk= fk_list_it++))
-      {
-        // FK_OPTION_RESTRICT and FK_OPTION_NO_ACTION only need read access
-        uint8 op= table_list->trg_event_map;
-        thr_lock_type lock_type;
-
-        if ((op & (1 << TRG_EVENT_DELETE) && fk_modifies_child(fk->delete_method))
-         || (op & (1 << TRG_EVENT_UPDATE) && fk_modifies_child(fk->update_method)))
-          lock_type= TL_WRITE_ALLOW_WRITE;
-        else
-          lock_type= TL_READ;
-
-        if (table_already_fk_prelocked(prelocking_ctx->query_tables,
-                                       fk->foreign_db, fk->foreign_table,
-                                       lock_type))
-          continue;
-
-        TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));
-        tl->init_one_table_for_prelocking(fk->foreign_db,
-                                          fk->foreign_table,
-                                          NULL, lock_type,
-                                          TABLE_LIST::PRELOCK_FK,
-                                          table_list->belong_to_view, op,
-                                          &prelocking_ctx->query_tables_last,
-                                          table_list->for_insert_data);
-      }
-      if (arena)
-        thd->restore_active_arena(arena, &backup);
+      Query_arena_stmt stmt(thd);
+      prelock_fk_tables(thd, table_list, prelocking_ctx,
+                        table->s->foreign_keys, true);
+      prelock_fk_tables(thd, table_list, prelocking_ctx,
+                        table->s->referenced_keys, false);
     }
   }
 
diff --git a/sql/table.h b/sql/table.h
index c674209c4d2..01c06e10405 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -653,6 +653,10 @@ struct TABLE_SHARE
   {
     return !referenced_keys.is_empty();
   }
+  bool has_foreign_keys() const
+  {
+    return !foreign_keys.is_empty();
+  }
 
   Virtual_column_info **check_constraints;
   uint	*blob_field;			/* Index to blobs in Field arrray*/