MXS-1775 Rearrange for moving main loop to MonitorInstance

This is another step in the process for moving the main loop
from MariaDBMonitor to MonitorInstance.

include/maxscale/monitor.hh

@@ -186,6 +186,20 @@ protected:
      */
     virtual void main();
 
+    /**
+     * @brief Called before the monitor loop is started
+     *
+     * The default implementation will load the journal and update @c m_master.
+     */
+    virtual void pre_loop();
+
+    /**
+     * @brief Called after the monitor loop has ended.
+     *
+     * The default implementation does nothing.
+     */
+    virtual void post_loop();
+
     MXS_MONITOR*          m_monitor;  /**< The generic monitor structure. */
     MXS_MONITORED_SERVER* m_master;   /**< Master server */
 

server/core/monitor.cc

@@ -2897,9 +2897,18 @@ void MonitorInstance::tick()
     atomic_add_uint64(&m_monitor->ticks, 1);
 }
 
-void MonitorInstance::main()
+void MonitorInstance::pre_loop()
 {
     load_server_journal(m_monitor, &m_master);
+}
+
+void MonitorInstance::post_loop()
+{
+}
+
+void MonitorInstance::main()
+{
+    pre_loop();
 
     while (!m_shutdown)
     {
@@ -2929,6 +2938,8 @@ void MonitorInstance::main()
             ms += MXS_MON_BASE_INTERVAL_MS;
         }
     }
+
+    post_loop();
 }
 
 //static

server/modules/monitor/mariadbmon/mariadbmon.cc

@@ -56,6 +56,7 @@ MariaDBMonitor::MariaDBMonitor(MXS_MONITOR* monitor)
     , m_external_master_port(PORT_UNKNOWN)
     , m_cluster_modified(true)
     , m_warn_set_standalone_master(true)
+    , m_log_no_master(true)
 {}
 
 MariaDBMonitor::~MariaDBMonitor()
@@ -280,12 +281,11 @@ void MariaDBMonitor::update_server_status(MXS_MONITORED_SERVER* monitored_server
     (*i).second->update_server(m_monitor);
 }
 
-void MariaDBMonitor::main()
+void MariaDBMonitor::pre_loop()
 {
-    MariaDBServer* root_master = NULL;
+    MonitorInstance::pre_loop();
-    int log_no_master = 1;
 
-    load_journal();
+    m_master = MonitorInstance::m_master ? get_server_info(MonitorInstance::m_master) : NULL;
 
     if (m_detect_replication_lag)
     {
@@ -302,6 +302,13 @@ void MariaDBMonitor::main()
         (*iter)->m_server_base->con = NULL;
     }
 
+    m_log_no_master = true;
+}
+
+void MariaDBMonitor::main()
+{
+    pre_loop();
+
     while (!should_shutdown())
     {
         atomic_add_uint64(&m_monitor->ticks, 1);
@@ -335,7 +342,7 @@ void MariaDBMonitor::main()
         }
 
         // Use the information to find the so far best master server.
-        root_master = find_root_master();
+        MariaDBServer* root_master = find_root_master();
 
         if (m_master != NULL && m_master->is_master())
         {
@@ -425,7 +432,7 @@ void MariaDBMonitor::main()
         }
 
          /* log master detection failure of first master becomes available after failure */
-        log_master_changes(root_master, &log_no_master);
+        log_master_changes(root_master);
 
         // Do not auto-join servers on this monitor loop if a failover (or any other cluster modification)
         // has been performed, as server states have not been updated yet. It will happen next iteration.
@@ -537,7 +544,7 @@ void MariaDBMonitor::measure_replication_lag(MariaDBServer* root_master)
     }
 }
 
-void MariaDBMonitor::log_master_changes(MariaDBServer* root_master_server, int* log_no_master)
+void MariaDBMonitor::log_master_changes(MariaDBServer* root_master_server)
 {
     MXS_MONITORED_SERVER* root_master = root_master_server ? root_master_server->m_server_base : NULL;
     if (root_master && mon_status_changed(root_master) &&
@@ -559,14 +566,14 @@ void MariaDBMonitor::log_master_changes(MariaDBServer* root_master_server, int*
                       root_master->server->address,
                       root_master->server->port);
         }
-        *log_no_master = 1;
+        m_log_no_master = true;
     }
     else
     {
-        if (!root_master && *log_no_master)
+        if (!root_master && m_log_no_master)
         {
             MXS_ERROR("No Master can be determined");
-            *log_no_master = 0;
+            m_log_no_master = false;
         }
     }
 }
@@ -857,17 +864,6 @@ void MariaDBMonitor::disable_setting(const char* setting)
     monitor_add_parameters(m_monitor, &p);
 }
 
-/**
- * Loads saved server states. Should only be called once at the beginning of the main loop after server
- * creation.
- */
-void MariaDBMonitor::load_journal()
-{
-    MXS_MONITORED_SERVER* master_output = NULL;
-    load_server_journal(m_monitor, &master_output);
-    m_master = master_output ? get_server_info(master_output) : NULL;
-}
-
 /**
  * Check sql text file parameters. A parameter should either be empty or a valid file which can be opened.
  *

server/modules/monitor/mariadbmon/mariadbmon.hh

@@ -100,6 +100,7 @@ public:
 
 protected:
     void update_server_status(MXS_MONITORED_SERVER* pMonitored_server);
+    void pre_loop();
     void main();
 
 private:
@@ -146,6 +147,7 @@ private:
     std::string m_script;            /**< Script to call when state changes occur on servers */
     uint64_t m_events;               /**< enabled events */
     bool m_warn_set_standalone_master; /**< Log a warning when setting standalone master */
+    bool m_log_no_master;            /**< Should it be logged that there is no master */
 
     enum slave_down_setting_t
     {
@@ -171,7 +173,7 @@ private:
     bool standalone_master_required();
     bool set_standalone_master();
     void assign_relay_master(MariaDBServer& serv_info);
-    void log_master_changes(MariaDBServer* root_master, int* log_no_master);
+    void log_master_changes(MariaDBServer* root_master);
     void update_gtid_domain();
     void update_external_master();
     void set_master_heartbeat(MariaDBServer*);
@@ -229,7 +231,6 @@ private:
 
     // Other methods
     void disable_setting(const char* setting);
-    void load_journal();
     bool check_sql_files();
     void enforce_read_only_on_slaves();
 };