MXS-2295: Session command loop test case

Test executes various session commands in a loop and makes sure a
COM_CHANGE_USER resets the history.

maxscale-system-test/CMakeLists.txt

@@ -915,6 +915,9 @@ add_test_executable(mxs2111_auth_string.cpp mxs2111_auth_string replication LABE
 # MXS-2115: Automatic version_string detection
 add_test_executable(mxs2115_version_string.cpp mxs2115_version_string replication LABELS REPL_BACKEND)
 
+# MXS-2295: COM_CHANGE_USER does not clear out session command history
+add_test_executable(mxs2295_change_user_loop.cpp mxs2295_change_user_loop mxs2295_change_user_loop LABELS REPL_BACKEND)
+
 ############################################
 # BEGIN: binlogrouter and avrorouter tests #
 ############################################

maxscale-system-test/cnf/maxscale.cnf.template.mxs2295_change_user_loop

@@ -0,0 +1,50 @@
+[maxscale]
+threads=###threads###
+log_info=1
+
+[server1]
+type=server
+address=###node_server_IP_1###
+port=###node_server_port_1###
+protocol=MySQLBackend
+
+[server2]
+type=server
+address=###node_server_IP_2###
+port=###node_server_port_2###
+protocol=MySQLBackend
+
+[server3]
+type=server
+address=###node_server_IP_3###
+port=###node_server_port_3###
+protocol=MySQLBackend
+
+[server4]
+type=server
+address=###node_server_IP_4###
+port=###node_server_port_4###
+protocol=MySQLBackend
+
+[MySQL Monitor]
+type=monitor
+module=mysqlmon
+servers=server1,server2,server3,server4
+user=maxskysql
+password=skysql
+monitor_interval=1000
+
+[RW Split Router]
+type=service
+router=readwritesplit
+servers=server1,server2,server3,server4
+user=maxskysql
+password=skysql
+max_sescmd_history=20
+disable_sescmd_history=false
+
+[RW Split Listener]
+type=listener
+service=RW Split Router
+protocol=MySQLClient
+port=4006

maxscale-system-test/mariadb_func.h

@@ -334,6 +334,16 @@ public:
         return mysql_error(m_conn);
     }
 
+    bool change_user(std::string user, std::string pw, std::string db = "test")
+    {
+        return mysql_change_user(m_conn, user.c_str(), pw.c_str(), db.c_str()) == 0;
+    }
+
+    bool reset_connection()
+    {
+        return change_user(m_user, m_pw, m_db);
+    }
+
 private:
     std::string m_host;
     int         m_port;

maxscale-system-test/mxs2295_change_user_loop.cpp

@@ -0,0 +1,66 @@
+/**
+ * MXS-2295: COM_CHANGE_USER does not clear out session command history
+ * https://jira.mariadb.org/browse/MXS-2295
+ */
+
+#include "testconnections.h"
+
+int main(int argc, char *argv[])
+{
+    TestConnections test(argc, argv);
+
+
+    Connection conn = test.maxscales->rwsplit();
+    test.expect(conn.connect(), "Connection failed: %s", conn.error());
+
+    for (int i = 0; i <= 300 && test.global_result == 0; i++)
+    {
+        if (i % 50 == 0)
+        {
+            test.tprintf("Iteration: %d", i);
+        }
+
+        test.set_timeout(60);
+
+        // Interleaved session commands, reads and "writes" (`SELECT @@last_insert_id` is treated as a master-only read)
+        test.expect(conn.query("SET @a = 1"), "Query failed: %s", conn.error());
+        test.expect(conn.query("USE test"), "Query failed: %s", conn.error());
+        test.expect(conn.query("SET SQL_MODE=''"), "Query failed: %s", conn.error());
+        test.expect(conn.query("USE test"), "Query failed: %s", conn.error());
+        test.expect(conn.query("SELECT @@last_insert_id"), "Query failed: %s", conn.error());
+        test.expect(conn.query("SELECT 1"), "Query failed: %s", conn.error());
+        test.expect(conn.query("USE test"), "Query failed: %s", conn.error());
+        test.expect(conn.query("SELECT 1"), "Query failed: %s", conn.error());
+
+        // User variable inside transaction
+        test.expect(conn.query("SET @a = 123"), "Query failed: %s", conn.error());
+        test.expect(conn.query("BEGIN"), "Query failed: %s", conn.error());
+        Row row = conn.row("SELECT @a");
+        test.expect(!row.empty() && row[0] == "123", "Invalid contents in user variable inside RW trx");
+        test.expect(conn.query("COMMIT"), "Query failed: %s", conn.error());
+
+        // User variable outside transaction
+        test.expect(conn.query("SET @a = 321"), "Query failed: %s", conn.error());
+        row = conn.row("SELECT @a");
+        test.expect(!row.empty() && row[0] == "321", "Invalid contents in user variable outside trx");
+
+        // User variable inside read-only transaction
+        test.expect(conn.query("SET @a = 456"), "Query failed: %s", conn.error());
+        test.expect(conn.query("START TRANSACTION READ ONLY"), "Query failed: %s", conn.error());
+        row = conn.row("SELECT @a");
+        test.expect(!row.empty() && row[0] == "456", "Invalid contents in user variable inside RO trx");
+        test.expect(conn.query("COMMIT"), "Query failed: %s", conn.error());
+
+        test.expect(conn.query("PREPARE ps FROM 'SELECT 1'"), "PREPARE failed: %s", conn.error());
+        row = conn.row("EXECUTE ps");
+        test.expect(!row.empty() && row[0] == "1", "Invalid contents in PS result");
+        test.expect(conn.query("DEALLOCATE PREPARE ps"), "DEALLOCATE failed: %s", conn.error());
+
+        test.expect(conn.reset_connection(), "Connection reset failed: %s", conn.error());
+    }
+
+    test.log_excludes(0, "Router session exceeded session command history limit");
+    test.log_includes(0, "Resetting session command history");
+
+    return test.global_result;
+}