MXS-1503: Test that no extra slaves are taken into use

Added a test that verifies that the slave connection count restrictions
work.

maxscale-system-test/CMakeLists.txt

@@ -599,6 +599,9 @@ add_test_executable(mxs1503_master_reconnection.cpp mxs1503_master_reconnection
 # Master reconnection with session commands
 add_test_executable(mxs1503_queued_sescmd.cpp mxs1503_queued_sescmd mxs1503_master_reconnection LABELS readwritesplit REPL_BACKEND)
 
+# Check that no extra slaves are taken into use
+add_test_executable(mxs1503_extra_slaves.cpp mxs1503_extra_slaves mxs1503_extra_slaves LABELS readwritesplit REPL_BACKEND)
+
 # MXS-1506: Delayed query retry
 # https://jira.mariadb.org/browse/MXS-1506
 add_test_executable(mxs1506_delayed_retry.cpp mxs1506_delayed_retry mxs1506_delayed_retry LABELS readwritesplit REPL_BACKEND)

maxscale-system-test/cnf/maxscale.cnf.template.mxs1503_extra_slaves

@@ -0,0 +1,59 @@
+[maxscale]
+threads=###threads###
+
+[MySQL Monitor]
+type=monitor
+module=mysqlmon
+###repl51###
+servers=server1,server2,server3,server4
+user=maxskysql
+passwd=skysql
+monitor_interval=1000
+
+[RW Split Router]
+type=service
+router=readwritesplit
+servers=server1,server2,server3,server4
+user=maxskysql
+passwd=skysql
+max_slave_connections=1
+
+[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/mariadb_func.cpp

@@ -525,6 +525,32 @@ int find_field(MYSQL* conn, const char* sql, const char* field_name, char* value
     return ret;
 }
 
+std::vector<std::string> get_row(MYSQL* conn, std::string sql)
+{
+    std::vector<std::string> rval;
+    MYSQL_RES* res;
+
+    if (mysql_query(conn, sql.c_str()) == 0 && (res = mysql_store_result(conn)))
+    {
+        MYSQL_ROW row = mysql_fetch_row(res);
+
+        if (row)
+        {
+            for (int i = 0; i < mysql_num_fields(res); i++)
+            {
+                rval.push_back(row[i]);
+            }
+        }
+        mysql_free_result(res);
+    }
+    else
+    {
+        printf("Error: Query failed: %s\n", mysql_error(conn));
+    }
+
+    return rval;
+}
+
 int get_int_version(std::string version)
 {
     std::istringstream str(version);

maxscale-system-test/mariadb_func.h

@@ -24,6 +24,7 @@
 #include <stdarg.h>
 #include <errno.h>
 #include <string>
+#include <vector>
 
 /**
  * Opens connection to DB: wropper over mysql_real_connect
@@ -204,6 +205,16 @@ int get_conn_num(MYSQL* conn, std::string ip, std::string hostname, std::string
  */
 int find_field(MYSQL* conn, const char* sql, const char* field_name, char* value);
 
+/**
+ * Execute a query and return the first row
+ *
+ * @param conn The connection to use
+ * @param sql  The query to execute
+ *
+ * @return The first row as a list of strings
+ */
+std::vector<std::string> get_row(MYSQL* conn, std::string sql);
+
 int get_int_version(std::string version);
 
 #endif // MARIADB_FUNC_H

maxscale-system-test/mxs1503_extra_slaves.cpp

@@ -0,0 +1,45 @@
+/**
+ * MXS-1503: Make sure no extra slaves are taken into use
+ *
+ * https://jira.mariadb.org/browse/MXS-1503
+ */
+#include "testconnections.h"
+#include <vector>
+#include <thread>
+#include <iostream>
+
+void query(MYSQL* conn, std::string q)
+{
+    execute_query(conn, "%s", q.c_str());
+    mysql_close(conn);
+}
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+    std::vector<std::thread> connections;
+
+    test.maxscales->connect();
+
+    auto original_row = get_row(test.maxscales->conn_rwsplit[0], "SELECT @@server_id");
+
+    for (int i = 0; i < 10; i++)
+    {
+        connections.emplace_back(query, test.maxscales->open_rwsplit_connection(), "SELECT SLEEP(10)");
+        sleep(1);
+        auto row = get_row(test.maxscales->conn_rwsplit[0], "SELECT @@server_id");
+        test.assert(row == original_row, "Value of @@server_id should not change: %s", row.at(0).c_str());
+    }
+
+    for (auto& a: connections)
+    {
+        a.join();
+        auto row = get_row(test.maxscales->conn_rwsplit[0], "SELECT @@server_id");
+        test.assert(row == original_row, "Value of @@server_id should not change: %s", row.at(0).c_str());
+    }
+
+
+    test.maxscales->disconnect();
+
+    return test.global_result;
+}