Avoid using obsolete functions in reset-replication

Removes some duplicate functions.

server/modules/monitor/mariadbmon/cluster_manipulation.cc

@@ -354,15 +354,35 @@ bool MariaDBMonitor::manual_reset_replication(SERVER* master_server, json_t** er
 
                 // Step 7: Set all slaves to replicate from the master.
                 // The following commands are only sent to slaves.
-                auto location = std::find(targets.begin(), targets.end(), new_master);
+                ServerArray slaves;
-                targets.erase(location);
+                for (auto target : targets)
-
-                // TODO: the following call does stop slave & reset slave again. Fix this later, although it
-                // doesn't cause error.
-                ServerArray dummy;
-                if ((size_t)redirect_slaves(new_master, targets, &dummy) == targets.size())
                 {
-                    // TODO: Properly check check slave IO/SQL threads.
+                    if (target != new_master)
+                    {
+                        slaves.push_back(target);
+                    }
+                }
+
+                if (!slaves.empty())
+                {
+                    SlaveStatus new_conn;
+                    SERVER* new_master_srv = new_master->m_server_base->server;
+                    new_conn.master_host = new_master_srv->address;
+                    new_conn.master_port = new_master_srv->port;
+                    GeneralOpData general(error_out, mxb::Duration(0.0)); // Expect this to complete quickly.
+                    size_t slave_conns_started = 0;
+                    for (auto slave : slaves)
+                    {
+                        if (slave->create_start_slave(general, new_conn))
+                        {
+                            slave_conns_started++;
+                        }
+                    }
+
+                    ServerArray dummy;
+                    if (slave_conns_started == slaves.size())
+                    {
+                        // TODO: Properly check slave IO/SQL threads.
                         MXS_NOTICE("All slaves redirected successfully.");
                     }
                     else
@@ -372,6 +392,7 @@ bool MariaDBMonitor::manual_reset_replication(SERVER* master_server, json_t** er
                                              "Some servers were not redirected to '%s'.", new_master->name());
                     }
                 }
+            }
             else
             {
                 error = true;
@@ -420,33 +441,6 @@ string MariaDBMonitor::generate_change_master_cmd(const string& master_host, int
     return change_cmd.str();
 }
 
-/**
- * Redirects slaves to replicate from another master server.
- *
- * @param new_master The replication master
- * @param slaves An array of slaves
- * @param redirected_slaves A vector where to insert successfully redirected slaves.
- * @return The number of slaves successfully redirected.
- */
-int MariaDBMonitor::redirect_slaves(MariaDBServer* new_master, const ServerArray& slaves,
-                                    ServerArray* redirected_slaves)
-{
-    mxb_assert(redirected_slaves != NULL);
-    MXS_NOTICE("Redirecting slaves to new master.");
-    string change_cmd = generate_change_master_cmd(new_master->m_server_base->server->address,
-                                                   new_master->m_server_base->server->port);
-    int successes = 0;
-    for (MariaDBServer* slave : slaves)
-    {
-        if (slave->redirect_one_slave(change_cmd))
-        {
-            successes++;
-            redirected_slaves->push_back(slave);
-        }
-    }
-    return successes;
-}
-
 /**
  * Redirect slave connections from the promotion target to replicate from the demotion target and vice versa.
  *

server/modules/monitor/mariadbmon/mariadbmon.hh

@@ -329,8 +329,7 @@ private:
                               int* id_missing_out) const;
 
     ServerArray get_redirectables(const MariaDBServer* old_master, const MariaDBServer* ignored_slave);
-    int         redirect_slaves(MariaDBServer* new_master, const ServerArray& slaves,
+
-                                ServerArray* redirected_slaves);
     int redirect_slaves_ex(GeneralOpData& op,
                            OperationType type,
                            const MariaDBServer* promotion_target,

server/modules/monitor/mariadbmon/mariadbserver.cc

@@ -767,37 +767,6 @@ bool MariaDBServer::can_replicate_from(MariaDBServer* master, string* reason_out
     return can_replicate;
 }
 
-bool MariaDBServer::redirect_one_slave(const string& change_cmd)
-{
-    bool success = false;
-    MYSQL* slave_conn = m_server_base->con;
-    const char* query = "STOP SLAVE;";
-    if (mxs_mysql_query(slave_conn, query) == 0)
-    {
-        query = "RESET SLAVE;";     // To erase any old I/O or SQL errors
-        if (mxs_mysql_query(slave_conn, query) == 0)
-        {
-            query = "CHANGE MASTER TO ...";     // Don't show the real query as it contains a password.
-            if (mxs_mysql_query(slave_conn, change_cmd.c_str()) == 0)
-            {
-                query = "START SLAVE;";
-                if (mxs_mysql_query(slave_conn, query) == 0)
-                {
-                    success = true;
-                    MXS_NOTICE("Slave '%s' redirected to new master.", name());
-                }
-            }
-        }
-    }
-
-    if (!success)
-    {
-        MXS_WARNING("Slave '%s' redirection failed: '%s'. Query: '%s'.",
-                    name(), mysql_error(slave_conn), query);
-    }
-    return success;
-}
-
 bool MariaDBServer::run_sql_from_file(const string& path, json_t** error_out)
 {
     MYSQL* conn = m_server_base->con;

server/modules/monitor/mariadbmon/mariadbserver.hh

@@ -300,14 +300,6 @@ public:
      */
     bool can_replicate_from(MariaDBServer* master, std::string* reason_out);
 
-    /**
-     * Redirect one slave server to another master
-     *
-     * @param change_cmd Change master command, usually generated by generate_change_master_cmd()
-     * @return True if slave accepted all commands
-     */
-    bool redirect_one_slave(const std::string& change_cmd);
-
     /**
      * Check if the server can be demoted by switchover.
      *