MXS-1760: Add use_sql_variables_in test case

The test checks that both text protocol and binary protocol statements
produce the correct result.

maxscale-system-test/CMakeLists.txt

@@ -618,6 +618,10 @@ add_test_executable(mxs1743_rconn_bitmask.cpp mxs1743_rconn_bitmask mxs1743_rcon
 # https://jira.mariadb.org/browse/MXS-1751
 add_test_executable(mxs1751_available_when_donor_crash.cpp mxs1751_available_when_donor_crash mxs1751_available_when_donor_crash LABELS GALERA_BACKEND)
 
+# MXS-1760: With use_sql_variables_in=master, unknown PS errors are logged
+# https://jira.mariadb.org/browse/MXS-1760
+add_test_executable(mxs1760_use_sql_variables_in.cpp mxs1760_use_sql_variables_in mxs1760_use_sql_variables_in LABELS readwritesplit REPL_BACKEND)
+
 # MXS-1773: Failing LOAD DATA LOCAL INFILE confuses readwritesplit
 # https://jira.mariadb.org/browse/MXS-1773
 add_test_executable(mxs1773_failing_ldli.cpp mxs1773_failing_ldli replication LABELS readwritesplit REPL_BACKEND)

maxscale-system-test/cnf/maxscale.cnf.template.mxs1760_use_sql_variables_in

@@ -0,0 +1,59 @@
+[maxscale]
+threads=###threads###
+
+[MySQL-Monitor]
+type=monitor
+module=mysqlmon
+###repl51###
+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
+use_sql_variables_in=master
+
+[RW-Split-Listener]
+type=listener
+service=RW-Split-Router
+protocol=MySQLClient
+port=4006
+
+[CLI]
+type=service
+router=cli
+
+[CLI-Listener]
+type=listener
+service=CLI
+protocol=maxscaled
+socket=default
+
+[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

maxscale-system-test/mxs1760_use_sql_variables_in.cpp

@@ -0,0 +1,68 @@
+/**
+* MXS-1760: Adding use_sql_variables_in=master resulted in error "Client requests unknown
+* prepared statement ID '0' that does not map to an internal ID"
+*
+* https://jira.mariadb.org/browse/MXS-1760
+*/
+
+#include "testconnections.h"
+#include <vector>
+#include <iostream>
+
+using namespace std;
+
+const int NUM_STMT = 2000;
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+    std::vector<MYSQL_STMT*> stmts;
+
+    test.maxscales->connect();
+
+    cout << "Setting variable @a to 123" << endl;
+    mysql_query(test.maxscales->conn_rwsplit[0], "SET @a = 123");
+    int rc = execute_query_check_one(test.maxscales->conn_rwsplit[0], "SELECT @a", "123");
+    test.assert(rc == 0, "Text protocol should return 123 as the value of @a");
+
+    cout << "Preparing and executing " << NUM_STMT << " prepared statements" << endl;
+    for (int i = 0; i < NUM_STMT && test.global_result == 0; i++)
+    {
+        stmts.push_back(mysql_stmt_init(test.maxscales->conn_rwsplit[0]));
+        MYSQL_STMT* stmt = stmts.back();
+        const char* query = "SELECT @a";
+        test.add_result(mysql_stmt_prepare(stmt, query, strlen(query)), "Failed to prepare: %s",
+                        mysql_stmt_error(stmt));
+    }
+
+    for (auto stmt: stmts)
+    {
+        char buffer[100] = "";
+        my_bool err = false;
+        my_bool isnull = false;
+        MYSQL_BIND bind[1] = {};
+
+        bind[0].buffer_length = sizeof(buffer);
+        bind[0].buffer = buffer;
+        bind[0].error = &err;
+        bind[0].is_null = &isnull;
+
+        // Execute a write, should return the master's server ID
+
+        test.add_result(mysql_stmt_execute(stmt), "Failed to execute: %s", mysql_stmt_error(stmt));
+        test.add_result(mysql_stmt_bind_result(stmt, bind), "Failed to bind result: %s", mysql_stmt_error(stmt));
+
+        while (mysql_stmt_fetch(stmt) == 0)
+        {
+            ;
+        }
+
+        test.add_result(strcmp(buffer, "123"), "Value is '%s', not '123'", buffer);
+        mysql_stmt_close(stmt);
+    }
+
+    test.maxscales->disconnect();
+    test.check_log_err(0, "unknown prepared statement", false);
+
+    return test.global_result;
+}