MW-388 Fix conflict handling of SPs with DECLARE ... HANDLER

It is possible for a stored procedure that has an error handler
that catches SQLEXCEPTION to call thd->clear_error() on a thd
that failed certification. And because the error is cleared,
wsrep patch proceeds with the normal path and may try to commit
statements that should actually abort.
This patch catches the situation where wsrep_conflict_state is
still set, but the thd's error has been cleared, and rolls back
the statement in such cases.

mysql-test/suite/galera/r/MW-388.result

+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY, f2 CHAR(255)) Engine=InnoDB;
+CREATE PROCEDURE insert_proc ()
+BEGIN
+DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
+BEGIN
+GET DIAGNOSTICS CONDITION 1 @errno = MYSQL_ERRNO;
+END;
+INSERT INTO t1 VALUES (1, 'node 1'),(2, 'node 1');
+INSERT INTO t1 VALUES (3, 'node 1');
+END|
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+INSERT INTO t1 VALUES (1, 'node 2');;
+SET SESSION DEBUG_SYNC = "now WAIT_FOR sync.wsrep_apply_cb_reached";
+SET SESSION wsrep_sync_wait = 0;
+SET SESSION DEBUG_SYNC = 'wsrep_before_replication SIGNAL wsrep_before_replication_reached WAIT_FOR wsrep_before_replication_continue';
+CALL insert_proc ();;
+SET SESSION DEBUG_SYNC = "now WAIT_FOR wsrep_before_replication_reached";
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL wsrep_before_replication_continue";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+SELECT @errno;
+@errno
+1213
+SELECT * FROM t1;
+f1	f2
+1	node 2
+3	node 1
+SELECT * FROM t1;
+f1	f2
+1	node 2
+3	node 1
+DROP TABLE t1;
+DROP PROCEDURE insert_proc;

mysql-test/suite/galera/t/MW-388.test

+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+
+--connection node_1
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY, f2 CHAR(255)) Engine=InnoDB;
+
+DELIMITER |;
+CREATE PROCEDURE insert_proc ()
+BEGIN
+        DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
+        BEGIN
+                GET DIAGNOSTICS CONDITION 1 @errno = MYSQL_ERRNO;
+        END;
+        INSERT INTO t1 VALUES (1, 'node 1'),(2, 'node 1');
+        INSERT INTO t1 VALUES (3, 'node 1');
+END|
+DELIMITER ;|
+
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+
+--connection node_2
+--send INSERT INTO t1 VALUES (1, 'node 2');
+
+--connect node_1a, 127.0.0.1, root, , test, $NODE_MYPORT_1
+--connection node_1a
+SET SESSION DEBUG_SYNC = "now WAIT_FOR sync.wsrep_apply_cb_reached";
+
+--connection node_1
+SET SESSION wsrep_sync_wait = 0;
+SET SESSION DEBUG_SYNC = 'wsrep_before_replication SIGNAL wsrep_before_replication_reached WAIT_FOR wsrep_before_replication_continue';
+--send CALL insert_proc ();
+
+--connection node_1a
+SET SESSION DEBUG_SYNC = "now WAIT_FOR wsrep_before_replication_reached";
+
+--connection node_1a
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL wsrep_before_replication_continue";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+
+--connection node_2
+--reap
+
+--connection node_1
+# We expect no errors here, because the handler in insert_proc() caught the deadlock error
+--reap
+SELECT @errno;
+SELECT * FROM t1;
+
+--connection node_2
+SELECT * FROM t1;
+
+DROP TABLE t1;
+DROP PROCEDURE insert_proc;
\ No newline at end of file

sql/sql_parse.cc

@@ -5620,6 +5620,26 @@ case SQLCOM_PREPARE:
     }
     if (thd->is_error() || (thd->variables.option_bits & OPTION_MASTER_SQL_ERROR))
       trans_rollback_stmt(thd);
+#ifdef WITH_WSREP
+    else if (thd->sp_runtime_ctx &&
+             !thd->is_error() &&
+             !thd->in_multi_stmt_transaction_mode() &&
+             (thd->wsrep_conflict_state == MUST_ABORT ||
+              thd->wsrep_conflict_state == CERT_FAILURE))
+    {
+      /*
+        The error was cleared, but THD was aborted by wsrep and
+        wsrep_conflict_state is still set accordingly. This
+        situation is expected if we are running a stored procedure
+        that declares a handler that catches ER_LOCK_DEADLOCK error.
+        In which case the error may have been cleared in method
+        sp_rcontext::handle_sql_condition().
+      */
+      trans_rollback_stmt(thd);
+      thd->wsrep_conflict_state= NO_CONFLICT;
+      thd->killed= THD::NOT_KILLED;
+    }
+#endif /* WITH_WSREP */
     else
     {
       /* If commit fails, we should be able to reset the OK status. */