MXS-1719 Add test that reveals problem

With the masking filter, several UPDATEs as one multi-statement
causes the session to hang.

maxscale-system-test/mxs1719.cpp

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2020-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include <iostream>
+#include "testconnections.h"
+
+using namespace std;
+
+namespace
+{
+
+void init(TestConnections& test)
+{
+    MYSQL* pMysql = test.maxscales->conn_rwsplit[0];
+
+    test.try_query(pMysql, "DROP TABLE IF EXISTS MXS_1719");
+    test.try_query(pMysql, "CREATE TABLE MXS_1719 (a TEXT, b TEXT)");
+    test.try_query(pMysql, "INSERT INTO MXS_1719 VALUES (1, 1)");
+}
+
+void run(TestConnections& test)
+{
+    init(test);
+
+    MYSQL* pMysql = mysql_init(NULL);
+    test.assert(pMysql, "Could not create MYSQL handle.");
+
+    const char* zHost = test.maxscales->IP[0];
+    const char* zUser = test.maxscales->user_name;
+    const char* zPassword = test.maxscales->password;
+    int port = test.maxscales->rwsplit_port[0];
+
+    if (mysql_real_connect(pMysql, test.maxscales->IP[0], zUser, zPassword, "test", port, NULL,
+                           CLIENT_MULTI_STATEMENTS))
+    {
+        // One multi-statement with two UPDATEs.
+        test.try_query(pMysql, "UPDATE MXS_1719 SET a=1; UPDATE MXS_1719 SET a=1;");
+        // This will hang immediately, so we can shorten the timeout.
+        test.set_timeout(5);
+        test.try_query(pMysql, "SELECT * FROM MXS_1719");
+    }
+    else
+    {
+        test.assert(false, "Could not connect to MaxScale.");
+    }
+}
+
+}
+
+int main(int argc, char* argv[])
+{
+    TestConnections::skip_maxscale_start(true);
+
+    TestConnections test(argc, argv);
+
+    if (test.maxscales->copy_to_node(0, "./mxs1719.json", "/home/vagrant/mxs1719.json") == 0)
+    {
+        if (test.maxscales->start() == 0)
+        {
+            if (test.maxscales->connect_rwsplit() == 0)
+            {
+                run(test);
+            }
+            else
+            {
+                test.assert(false, "Could not connect to RWS.");
+            }
+        }
+        else
+        {
+            test.assert(false, "Could not start MaxScale.");
+        }
+    }
+    else
+    {
+        test.assert(false, "Could not copy masking file to MaxScale node.");
+    }
+
+    return test.global_result;
+}