MDEV-15888 Implement FLUSH TABLES tbl_name [, tbl_name] ... WITH READ LOCK for views.

Enable the FLUSH TABLES for views. It works now.

mysql-test/main/flush-innodb.result

@@ -60,7 +60,7 @@ DROP TABLE export;
 CREATE VIEW v1 AS SELECT 1;
 CREATE TEMPORARY TABLE t1 (a INT);
 FLUSH TABLES v1 FOR EXPORT;
-ERROR HY000: 'test.v1' is not of type 'BASE TABLE'
+UNLOCK TABLES;
 FLUSH TABLES t1 FOR EXPORT;
 ERROR 42S02: Table 'test.t1' doesn't exist
 FLUSH TABLES non_existent FOR EXPORT;

mysql-test/main/flush-innodb.test

@@ -93,8 +93,8 @@ DROP TABLE export;
 CREATE VIEW v1 AS SELECT 1;
 CREATE TEMPORARY TABLE t1 (a INT);
 
---error ER_WRONG_OBJECT
 FLUSH TABLES v1 FOR EXPORT;
+UNLOCK TABLES;
 --error ER_NO_SUCH_TABLE
 FLUSH TABLES t1 FOR EXPORT;
 --error ER_NO_SUCH_TABLE

mysql-test/main/flush.result

@@ -295,16 +295,16 @@ create view v1 as select 1;
 create view v2 as select * from t1;
 create view v3 as select * from v2;
 flush table v1, v2, v3 with read lock;
-ERROR HY000: 'test.v1' is not of type 'BASE TABLE'
+unlock tables;
 flush table v1 with read lock;
-ERROR HY000: 'test.v1' is not of type 'BASE TABLE'
+unlock tables;
 flush table v2 with read lock;
-ERROR HY000: 'test.v2' is not of type 'BASE TABLE'
+unlock tables;
 flush table v3 with read lock;
-ERROR HY000: 'test.v3' is not of type 'BASE TABLE'
+unlock tables;
 create temporary table v1 (a int);
 flush table v1 with read lock;
-ERROR HY000: 'test.v1' is not of type 'BASE TABLE'
+unlock tables;
 drop view v1;
 create table v1 (a int);
 flush table v1 with read lock;
@@ -556,6 +556,56 @@ UNLOCK TABLES;
 DROP VIEW v1;
 DROP TABLE t1;
 #
+# MDEV-15888 Implement FLUSH TABLES tbl_name [, tbl_name] ... WITH READ LOCK for views.
+#
+create table t1 (a int);
+insert into t1 values (1), (2), (3);
+create view v1 as select * from t1;
+create view v2 as select * from v1;
+flush table v1 with read lock;
+connect con1, localhost, root;
+insert into v1 values (4);
+connection default;
+# Wait until INSERT starts to wait for FTWRL to go away.
+select * from t1;
+a
+1
+2
+3
+unlock tables;
+connection con1;
+connection default;
+select * from t1;
+a
+1
+2
+3
+4
+flush table v2 with read lock;
+connection con1;
+insert into t1 values (5);
+connection default;
+# Wait until INSERT starts to wait for FTWRL to go away.
+select * from t1;
+a
+1
+2
+3
+4
+unlock tables;
+connection con1;
+connection default;
+select * from t1;
+a
+1
+2
+3
+4
+5
+drop view v1, v2;
+drop table t1;
+disconnect con1;
+#
 # Test FLUSH THREADS
 #
 flush threads;

mysql-test/main/flush.test

@@ -377,17 +377,17 @@ create view v1 as select 1;
 create view v2 as select * from t1;
 create view v3 as select * from v2;
 
---error ER_WRONG_OBJECT
 flush table v1, v2, v3 with read lock;
---error ER_WRONG_OBJECT
+unlock tables;
 flush table v1 with read lock;
---error ER_WRONG_OBJECT
+unlock tables;
 flush table v2 with read lock;
---error ER_WRONG_OBJECT
+unlock tables;
 flush table v3 with read lock;
+unlock tables;
 create temporary table v1 (a int);
---error ER_WRONG_OBJECT
 flush table v1 with read lock;
+unlock tables;
 drop view v1;
 create table v1 (a int);
 flush table v1 with read lock;
@@ -669,6 +669,60 @@ UNLOCK TABLES;
 DROP VIEW v1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-15888 Implement FLUSH TABLES tbl_name [, tbl_name] ... WITH READ LOCK for views.
+--echo #
+
+create table t1 (a int);
+insert into t1 values (1), (2), (3);
+create view v1 as select * from t1;
+create view v2 as select * from v1;
+
+flush table v1 with read lock;
+connect(con1, localhost, root);
+--send insert into v1 values (4)
+--sleep 1
+connection default;
+--echo # Wait until INSERT starts to wait for FTWRL to go away.
+let $wait_condition=
+  select count(*) = 1 from information_schema.processlist
+  where state = "Waiting for table metadata lock"
+  and info = "insert into v1 values (4)";
+--source include/wait_condition.inc
+select * from t1;
+unlock tables;
+
+connection con1;
+reap;
+
+connection default;
+select * from t1;
+
+flush table v2 with read lock;
+connection con1;
+--send insert into t1 values (5)
+--sleep 1
+connection default;
+--echo # Wait until INSERT starts to wait for FTWRL to go away.
+let $wait_condition=
+  select count(*) = 1 from information_schema.processlist
+  where state = "Waiting for table metadata lock"
+  and info = "insert into t1 values (5)";
+--source include/wait_condition.inc
+select * from t1;
+unlock tables;
+
+connection con1;
+reap;
+
+connection default;
+select * from t1;
+
+drop view v1, v2;
+drop table t1;
+disconnect con1;
+
+
 --echo #
 --echo # Test FLUSH THREADS
 --echo #

sql/sql_reload.cc

@@ -592,7 +592,8 @@ bool flush_tables_with_read_lock(THD *thd, TABLE_LIST *all_tables)
     for (TABLE_LIST *table_list= all_tables; table_list;
          table_list= table_list->next_global)
     {
-      if (!(table_list->table->file->ha_table_flags() & HA_CAN_EXPORT))
+      if (!(table_list->is_view() ||
+            table_list->table->file->ha_table_flags() & HA_CAN_EXPORT))
       {
         my_error(ER_ILLEGAL_HA, MYF(0),table_list->table->file->table_type(),
                  table_list->db.str, table_list->table_name.str);
@@ -606,7 +607,8 @@ bool flush_tables_with_read_lock(THD *thd, TABLE_LIST *all_tables)
     for (auto table_list= all_tables; table_list;
          table_list= table_list->next_global)
     {
-      if (table_list->table->file->extra(HA_EXTRA_FLUSH))
+      if (!table_list->is_view() &&
+          table_list->table->file->extra(HA_EXTRA_FLUSH))
         goto error_reset_bits;
     }
   }

sql/sql_yacc.yy

@@ -14426,8 +14426,6 @@ opt_flush_lock:
           for (; tables; tables= tables->next_global)
           {
             tables->mdl_request.set_type(MDL_SHARED_NO_WRITE);
-            /* Don't try to flush views. */
-            tables->required_type= TABLE_TYPE_NORMAL;
             /* Ignore temporary tables. */
             tables->open_type= OT_BASE_ONLY;
           }