MDEV-24255 MTR test galera_bf_abort fails with --ps-protocol

Under ps-protocol, commandsl like COM_STMT_FETCH, COM_STMT_CLOSE and
COM_STMT_SEND_LONG_DATA are not supposed to return errors. Therefore,
if a transaction is BF aborted and the client is processing one of
those commands, then we should not return a deadlock error
immediately. Instead wait for the a subsequent client interaction
which permits errors to be returned. To handle this,
wsrep_before_command() now accepts parameter keep_command_error. If
set true, keep_command_error will cause wsrep-lib side to skip result
handling, and to keep the current error for the next interaction with
the client.

Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

mysql-test/suite/galera/r/galera#500.result

@@ -1,5 +1,3 @@
-connection node_1;
-connection node_2;
 connection node_2;
 connection node_1;
 connection node_1;

mysql-test/suite/galera/r/galera_bf_abort_ps.result

@@ -0,0 +1,16 @@
+connection node_2;
+connection node_1;
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY, f2 CHAR(6)) ENGINE=InnoDB;
+connect node_2a, 127.0.0.1, root, , test, $NODE_MYPORT_2;
+connection node_2;
+START TRANSACTION;
+INSERT INTO t1 VALUES (1,'node_2');
+connection node_1;
+INSERT INTO t1 VALUES (1,'node_1');
+connection node_2a;
+connection node_2;
+INSERT INTO t1 VALUES (2, 'node_2');
+ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
+wsrep_local_aborts_increment
+1
+DROP TABLE t1;

mysql-test/suite/galera/r/galera_bf_abort_ps_threadpool.result

@@ -0,0 +1,22 @@
+connection node_2;
+connection node_1;
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY, f2 CHAR(6)) ENGINE=InnoDB;
+connect node_2a, 127.0.0.1, root, , test, $NODE_MYPORT_2;
+connection node_2;
+START TRANSACTION;
+INSERT INTO t1 VALUES (1,'node_2');
+connection node_2a;
+SET GLOBAL debug_dbug = "+d,sync.wsrep_apply_cb";
+connection node_1;
+INSERT INTO t1 VALUES (1,'node_1');
+connection node_2a;
+SET DEBUG_SYNC = "now WAIT_FOR sync.wsrep_apply_cb_reached";
+connection node_2;
+SET DEBUG_SYNC = "wsrep_before_before_command SIGNAL signal.wsrep_apply_cb WAIT_FOR bf_abort";
+INSERT INTO t1 VALUES (2, 'node_2');
+ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
+wsrep_local_aborts_increment
+1
+SET DEBUG_SYNC = 'RESET';
+SET GLOBAL debug_dbug = DEFAULT;
+DROP TABLE t1;

mysql-test/suite/galera/t/galera_bf_abort_ps.cnf

@@ -0,0 +1,3 @@
+!include ../galera_2nodes.cnf
+[mysqltest]
+ps-protocol

mysql-test/suite/galera/t/galera_bf_abort_ps.test

@@ -0,0 +1,34 @@
+#
+# MDEV-24255
+# Test BF abort of a transaction that has ps-protocol enabled
+#
+
+--source include/galera_cluster.inc
+
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY, f2 CHAR(6)) ENGINE=InnoDB;
+--connect node_2a, 127.0.0.1, root, , test, $NODE_MYPORT_2
+
+--connection node_2
+--let $wsrep_local_bf_aborts_before = `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_local_bf_aborts'`
+
+START TRANSACTION;
+INSERT INTO t1 VALUES (1,'node_2');
+
+--connection node_1
+INSERT INTO t1 VALUES (1,'node_1');
+
+--connection node_2a
+--let $wait_condition = SELECT COUNT(*) = 1 FROM t1 WHERE f2 = 'node_1'
+--source include/wait_condition.inc
+
+--connection node_2
+--error ER_LOCK_DEADLOCK
+INSERT INTO t1 VALUES (2, 'node_2');
+
+--let $wsrep_local_bf_aborts_after = `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_local_bf_aborts'`
+
+--disable_query_log
+--eval SELECT $wsrep_local_bf_aborts_after - $wsrep_local_bf_aborts_before = 1 AS wsrep_local_aborts_increment;
+--enable_query_log
+
+DROP TABLE t1;

mysql-test/suite/galera/t/galera_bf_abort_ps_threadpool.cnf

@@ -0,0 +1,7 @@
+!include ../galera_2nodes.cnf
+
+[mysqld]
+thread-handling=pool-of-threads
+
+[mysqltest]
+ps-protocol

mysql-test/suite/galera/t/galera_bf_abort_ps_threadpool.test

@@ -0,0 +1,54 @@
+#
+# MDEV-24255
+# Test BF abort of a transaction that has ps-protocol enabled
+# This test stresses the case where wsrep_before_command()
+# finds the transaction in state s_must_abort. This only
+# possible when the server is using the thread pool.
+#
+
+--source include/galera_cluster.inc
+--source include/have_debug_sync.inc
+
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY, f2 CHAR(6)) ENGINE=InnoDB;
+
+--connect node_2a, 127.0.0.1, root, , test, $NODE_MYPORT_2
+
+--connection node_2
+--let $wsrep_local_bf_aborts_before = `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_local_bf_aborts'`
+
+START TRANSACTION;
+INSERT INTO t1 VALUES (1,'node_2');
+
+--connection node_2a
+SET GLOBAL debug_dbug = "+d,sync.wsrep_apply_cb";
+
+--connection node_1
+INSERT INTO t1 VALUES (1,'node_1');
+
+--connection node_2a
+SET DEBUG_SYNC = "now WAIT_FOR sync.wsrep_apply_cb_reached";
+
+--connection node_2
+SET DEBUG_SYNC = "wsrep_before_before_command SIGNAL signal.wsrep_apply_cb WAIT_FOR bf_abort";
+
+#
+# The following INSERT is expected to enter
+# wsrep_before_command() and find its transaction
+# in state s_must_abort.
+# Notice that the test appears more complicated
+# than it needs to... however we cannot use
+# --send for this INSERT, otherwise mysqltest
+# will not use ps-protocol
+#
+--error ER_LOCK_DEADLOCK
+INSERT INTO t1 VALUES (2, 'node_2');
+
+--let $wsrep_local_bf_aborts_after = `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_local_bf_aborts'`
+
+--disable_query_log
+--eval SELECT $wsrep_local_bf_aborts_after - $wsrep_local_bf_aborts_before = 1 AS wsrep_local_aborts_increment;
+--enable_query_log
+
+SET DEBUG_SYNC = 'RESET';
+SET GLOBAL debug_dbug = DEFAULT;
+DROP TABLE t1;

sql/sql_parse.cc

@@ -1164,6 +1164,14 @@ static bool wsrep_tables_accessible_when_detached(const TABLE_LIST *tables)
   }
   return true;
 }
+
+static bool wsrep_command_no_result(char command)
+{
+  return (command == COM_STMT_PREPARE          ||
+          command == COM_STMT_FETCH            ||
+          command == COM_STMT_SEND_LONG_DATA   ||
+          command == COM_STMT_CLOSE);
+}
 #endif /* WITH_WSREP */
 #ifndef EMBEDDED_LIBRARY
 
@@ -1287,12 +1295,20 @@ bool do_command(THD *thd)
 #ifdef WITH_WSREP
   DEBUG_SYNC(thd, "wsrep_before_before_command");
   /*
-    Aborted by background rollbacker thread.
-    Handle error here and jump straight to out
+    If this command does not return a result, then we
+    instruct wsrep_before_command() to skip result handling.
+    This causes BF aborted transaction to roll back but keep
+    the error state until next command which is able to return
+    a result to the client.
   */
-  if (wsrep_before_command(thd))
+  if (wsrep_before_command(thd, wsrep_command_no_result(command)))
   {
-    thd->store_globals();
+    /*
+      Aborted by background rollbacker thread.
+      Handle error here and jump straight to out.
+      Notice that thd->store_globals() is called
+      in wsrep_before_command().
+    */
     WSREP_LOG_THD(thd, "enter found BF aborted");
     DBUG_ASSERT(!thd->mdl_context.has_locks());
     DBUG_ASSERT(!thd->get_stmt_da()->is_set());
@@ -2384,12 +2400,7 @@ dispatch_end:
     WSREP_DEBUG("THD is killed at dispatch_end");
   }
   wsrep_after_command_before_result(thd);
-  if (wsrep_current_error(thd) &&
-      !(command == COM_STMT_PREPARE          ||
-        command == COM_STMT_FETCH            ||
-        command == COM_STMT_SEND_LONG_DATA   ||
-        command == COM_STMT_CLOSE
-        ))
+  if (wsrep_current_error(thd) && !wsrep_command_no_result(command))
   {
     /* todo: Pass wsrep client state current error to override */
     wsrep_override_error(thd, wsrep_current_error(thd),

sql/wsrep_trans_observer.h

@@ -442,11 +442,17 @@ wsrep_wait_rollback_complete_and_acquire_ownership(THD *thd)
   DBUG_VOID_RETURN;
 }
 
-static inline int wsrep_before_command(THD* thd)
+static inline int wsrep_before_command(THD* thd, bool keep_command_error)
 {
   return (thd->wsrep_cs().state() != wsrep::client_state::s_none ?
-	  thd->wsrep_cs().before_command() : 0);
+	  thd->wsrep_cs().before_command(keep_command_error) : 0);
 }
+
+static inline int wsrep_before_command(THD* thd)
+{
+  return wsrep_before_command(thd, false);
+}
+
 /*
   Called after each command.
 

wsrep-lib

@@ -1 +1 @@
-Subproject commit 41a6e9dad79c921134e44cf974b6b7ca3b84e538
+Subproject commit dcf3ce91cdb9d254ae04ecc6a2f91f46b171280d