MDEV-7894 - ALTER TABLE ... IMPORT/DISCARD TABLESPACE under LOCK TABLES doesn'tbb-mdev7894

            acquire X metadata lock

Due to coding mistake thr_lock.c lock was necessary to isolate ALTER TABLE
IMPORT/DISCARD TABLESPACE under LOCK TABLES from concurrent I_S queries/
open HANDLERs.

Change ALTER TABLE IMPORT/DISCARD TABLESPACE code to acquire X
lock on table being imported/discarded even under lock tables.

1 files changed, 126 insertions, 0 deletions

diff --git a/mysql-test/r/alter_table.result b/mysql-test/r/alter_table.result
index 544e64e6373..9bbb525cc2e 100644
--- a/mysql-test/r/alter_table.result
+++ b/mysql-test/r/alter_table.result
@@ -2007,3 +2007,129 @@ INSERT INTO t1 VALUES (1),(2),(3),(4),(5),(6),(7),(8);
 INSERT INTO t1 SELECT a.* FROM t1 a, t1 b, t1 c, t1 d, t1 e;
 ALTER TABLE t1 MODIFY i FLOAT;
 DROP TABLE t1;
+#
+# Coverage for changes to ALTER TABLE ... IMPORT/DISCARD TABLESPACE
+# code introduced by WL#6671 "Improve scalability by not using
+# thr_lock.c locks for InnoDB tables".
+#
+# Check that ALTER TABLE ... IMPORT/DISCARD TABLESPACE acquires X
+# metadata lock on the table even when executed under LOCK TABLES.
+#
+# Suppress error messages which will be generated by IMPORT TABLESPACE
+call mtr.add_suppression("InnoDB: Trying to import a tablespace, but could not open the tablespace file");
+call mtr.add_suppression("InnoDB: Operating system error number 2 in a file operation.");
+call mtr.add_suppression("InnoDB: The error means the system cannot find the path specified.");
+CREATE TABLE t1 (i INT) ENGINE=InnoDB;
+#
+# 1) Check that ALTER TABLE ... IMPORT/DISCARD TABLESPACE on
+#    base table acquire X lock (when not under LOCK TABLES).
+#
+connect con1, localhost, root;
+# Acquire S lock on table 't1'.
+HANDLER t1 OPEN;
+connect con2, localhost, root;
+# Sending:
+ALTER TABLE t1 DISCARD TABLESPACE;
+connection default;
+# Wait until ALTER TABLE is blocked since it tries to acquire X lock.
+connection con1;
+# Unblock ALTER TABLE DISCARD
+HANDLER t1 CLOSE;
+connection con2;
+# Reaping ALTER TABLE DISCARD
+connection con1;
+# Acquire S lock on table 't1'.
+HANDLER t1 OPEN;
+connection con2;
+# Sending:
+ALTER TABLE t1 IMPORT TABLESPACE;
+connection default;
+# Wait until ALTER TABLE is blocked since it tries to acquire X lock.
+connection con1;
+# Unblock ALTER TABLE IMPORT
+HANDLER t1 CLOSE;
+connection con2;
+# Reaping ALTER TABLE IMPORT
+# It should fail as no tablespace was copied after DISCARD.
+ERROR 42S02: Table 'test.t1' doesn't exist in engine
+connection default;
+DROP TABLE t1;
+#
+# 2) ALTER TABLE ... IMPORT/DISCARD TABLESPACE on temporary table
+#    should not try to acquire X metadata lock on base table.
+#
+CREATE TABLE t1 (i INT) ENGINE=InnoDB;
+connection con1;
+# Acquire S lock on table 't1'.
+HANDLER t1 OPEN;
+connection con2;
+CREATE TEMPORARY TABLE t1 (j INT) ENGINE=InnoDB;
+# Both DISCARD and IMPORT on temporary table should fail without
+# acquiring any locks and blocking.
+# NOTE: they don't fail in MariaDB yet, still we test for locks.
+ALTER TABLE t1 DISCARD TABLESPACE;
+ALTER TABLE t1 IMPORT TABLESPACE;
+ERROR 42S02: Table 'test.t1' doesn't exist in engine
+DROP TEMPORARY TABLE t1;
+#
+# 3) Check that ALTER TABLE ... IMPORT/DISCARD TABLESPACE on
+#    base table under LOCK TABLES acquire X lock.
+#
+connection con2;
+LOCK TABLES t1 WRITE;
+# Sending:
+ALTER TABLE t1 DISCARD TABLESPACE;
+connection default;
+# Wait until ALTER TABLE is blocked since it tries to acquire X lock.
+connection con1;
+# Unblock ALTER TABLE DISCARD
+HANDLER t1 CLOSE;
+connection con2;
+# Reaping ALTER TABLE DISCARD
+connection con1;
+# Acquire S lock on table 't1'.
+HANDLER t1 OPEN;
+connection con2;
+# Sending:
+ALTER TABLE t1 IMPORT TABLESPACE;
+connection default;
+# Wait until ALTER TABLE is blocked since it tries to acquire X lock.
+connection con1;
+# Unblock ALTER TABLE IMPORT
+HANDLER t1 CLOSE;
+connection con2;
+# Reaping ALTER TABLE IMPORT
+# It should fail as no tablespace was copied after DISCARD.
+ERROR 42S02: Table 'test.t1' doesn't exist in engine
+UNLOCK TABLES;
+connection default;
+DROP TABLE t1;
+#
+# 4) Under LOCK TABLES, ALTER TABLE ... IMPORT/DISCARD TABLESPACE on
+#    temporary table should not try to acquire X metadata lock on base
+#    table.
+#
+CREATE TABLE t1 (i INT) ENGINE=InnoDB;
+connection con1;
+# Acquire S lock on table 't1'.
+HANDLER t1 OPEN;
+connection con2;
+CREATE TEMPORARY TABLE t1 (j INT) ENGINE=InnoDB;
+LOCK TABLES t1 WRITE;
+# Both DISCARD and IMPORT on temporary table should fail without
+# acquiring any locks and blocking.
+# NOTE: they don't fail in MariaDB yet, still we test for locks.
+ALTER TABLE t1 DISCARD TABLESPACE;
+ALTER TABLE t1 IMPORT TABLESPACE;
+ERROR 42S02: Table 'test.t1' doesn't exist in engine
+UNLOCK TABLES;
+DROP TEMPORARY TABLE t1;
+connection con1;
+HANDLER t1 CLOSE;
+#
+# Clean-up.
+#
+disconnect con1;
+disconnect con2;
+connection default;
+DROP TABLE t1;