From fb217449dce9f6996563d5aa257be01c12df4a11 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marko=20M=C3=A4kel=C3=A4?= <marko.makela@mariadb.com>
Date: Tue, 31 Mar 2020 15:10:54 +0300
Subject: [PATCH] MDEV-13626: Import and adapt innodb.xa_recovery_debug

Adapt the test that was added in
mysql/mysql-server@6b65d9032cbb6c1016cb09d056df6885e3d25dc6
but omitted in commit 2e814d4702d71a04388386a9f591d14a35980bfe.

Instead of triggering a log checkpoint, we will only trigger
a redo log flush before killing the server.
Note: the mtr.commit() call in trx_rollback_for_mysql()
will not actually make the undo log header page state change durable.
A call to log_write_up_to(mtr.commit_lsn(), true) would do that.

It is unclear what the originally reported bug scenario was.
As long as innobase_rollback_by_xid() will not return without
ensuring that the redo log has been durably written, we should be safe.
---
 .../suite/innodb/r/xa_recovery_debug.result   | 27 ++++++++++++++
 .../suite/innodb/t/xa_recovery_debug.test     | 35 +++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 mysql-test/suite/innodb/r/xa_recovery_debug.result
 create mode 100644 mysql-test/suite/innodb/t/xa_recovery_debug.test

diff --git a/mysql-test/suite/innodb/r/xa_recovery_debug.result b/mysql-test/suite/innodb/r/xa_recovery_debug.result
new file mode 100644
index 00000000000..082fc96e198
--- /dev/null
+++ b/mysql-test/suite/innodb/r/xa_recovery_debug.result
@@ -0,0 +1,27 @@
+#
+# Bug#20872655 XA ROLLBACK IS NOT CRASH-SAFE
+#
+CREATE TABLE t(a INT PRIMARY KEY, b INT UNIQUE) ENGINE=INNODB;
+INSERT INTO t SET a=0;
+connect  con1,localhost,root;
+XA START 'zombie';
+INSERT INTO t SET a=1;
+UPDATE t SET b=1 WHERE a=1;
+SELECT COUNT(*) FROM t;
+COUNT(*)
+2
+XA END 'zombie';
+XA PREPARE 'zombie';
+SET DEBUG_SYNC='trx_xa_rollback SIGNAL s1 WAIT_FOR s2';
+XA ROLLBACK 'zombie';
+connection default;
+SET DEBUG_SYNC='now WAIT_FOR s1';
+SET GLOBAL innodb_flush_log_at_trx_commit=1;
+DELETE FROM t LIMIT 1;
+disconnect con1;
+XA COMMIT 'zombie';
+ERROR XAE04: XAER_NOTA: Unknown XID
+SELECT COUNT(*) FROM t;
+COUNT(*)
+0
+DROP TABLE t;
diff --git a/mysql-test/suite/innodb/t/xa_recovery_debug.test b/mysql-test/suite/innodb/t/xa_recovery_debug.test
new file mode 100644
index 00000000000..8b1f188a0e3
--- /dev/null
+++ b/mysql-test/suite/innodb/t/xa_recovery_debug.test
@@ -0,0 +1,35 @@
+--source include/have_innodb.inc
+--source include/have_debug.inc
+--source include/have_debug_sync.inc
+# Embedded server does not support restarting
+--source include/not_embedded.inc
+
+--echo #
+--echo # Bug#20872655 XA ROLLBACK IS NOT CRASH-SAFE
+--echo #
+
+CREATE TABLE t(a INT PRIMARY KEY, b INT UNIQUE) ENGINE=INNODB;
+INSERT INTO t SET a=0;
+connect (con1,localhost,root);
+XA START 'zombie';
+INSERT INTO t SET a=1;
+UPDATE t SET b=1 WHERE a=1;
+SELECT COUNT(*) FROM t;
+XA END 'zombie';
+XA PREPARE 'zombie';
+SET DEBUG_SYNC='trx_xa_rollback SIGNAL s1 WAIT_FOR s2';
+--send XA ROLLBACK 'zombie'
+connection default;
+SET DEBUG_SYNC='now WAIT_FOR s1';
+# Ensure that the state change from XA PREPARE to ACTIVE gets flushed
+# to the redo log. Without this, it could be that we will recover to
+# a state that precedes the start of the XA ROLLBACK.
+SET GLOBAL innodb_flush_log_at_trx_commit=1;
+DELETE FROM t LIMIT 1;
+let $shutdown_timeout=0;
+--source include/restart_mysqld.inc
+disconnect con1;
+--error ER_XAER_NOTA
+XA COMMIT 'zombie';
+SELECT COUNT(*) FROM t;
+DROP TABLE t;