MXS-1775 Make MariaDBMon non-dependent on stop() return value

To align it with the behavour or MonitorInstance::stop()

include/maxscale/monitor.hh

@@ -42,6 +42,18 @@ public:
      */
     int32_t state() const;
 
+    /**
+     * @brief Find out whether the monitor is running.
+     *
+     * @return True, if the monitor is running, false otherwise.
+     *
+     * @see state().
+     */
+    bool is_running() const
+    {
+        return state() == MXS_MONITOR_RUNNING;
+    }
+
     /**
      * @brief Starts the monitor.
      *

server/modules/monitor/mariadbmon/cluster_manipulation.cc

@@ -25,9 +25,10 @@ static void print_redirect_errors(MariaDBServer* first_server, const ServerArray
 
 bool MariaDBMonitor::manual_switchover(SERVER* new_master, SERVER* current_master, json_t** error_out)
 {
-    bool stopped = stop();
+    bool running = is_running();
-    if (stopped)
+    if (running)
     {
+        stop();
         MXS_NOTICE("Stopped the monitor %s for the duration of switchover.", m_monitor_base->name);
     }
     else
@@ -69,7 +70,7 @@ bool MariaDBMonitor::manual_switchover(SERVER* new_master, SERVER* current_maste
         }
     }
 
-    if (stopped)
+    if (running)
     {
         // TODO: What if this fails?
         start(m_monitor_base->parameters);
@@ -79,9 +80,10 @@ bool MariaDBMonitor::manual_switchover(SERVER* new_master, SERVER* current_maste
 
 bool MariaDBMonitor::manual_failover(json_t** output)
 {
-    bool stopped = stop();
+    bool running = is_running();
-    if (stopped)
+    if (running)
     {
+        stop();
         MXS_NOTICE("Stopped monitor %s for the duration of failover.", m_monitor_base->name);
     }
     else
@@ -104,7 +106,7 @@ bool MariaDBMonitor::manual_failover(json_t** output)
         }
     }
 
-    if (stopped)
+    if (running)
     {
         // TODO: What if this fails?
         start(m_monitor_base->parameters);
@@ -114,9 +116,10 @@ bool MariaDBMonitor::manual_failover(json_t** output)
 
 bool MariaDBMonitor::manual_rejoin(SERVER* rejoin_server, json_t** output)
 {
-    bool stopped = stop();
+    bool running = is_running();
-    if (stopped)
+    if (running)
     {
+        stop();
         MXS_NOTICE("Stopped monitor %s for the duration of rejoin.", m_monitor_base->name);
     }
     else
@@ -178,7 +181,7 @@ bool MariaDBMonitor::manual_rejoin(SERVER* rejoin_server, json_t** output)
         PRINT_MXS_JSON_ERROR(output, BAD_CLUSTER, m_monitor_base->name);
     }
 
-    if (stopped)
+    if (running)
     {
         // TODO: What if this fails?
         start(m_monitor_base->parameters);

server/modules/monitor/mariadbmon/mariadbmon.cc

@@ -55,6 +55,7 @@ MariaDBMonitor::MariaDBMonitor(MXS_MONITOR* monitor_base)
     : m_monitor_base(monitor_base)
     , m_id(config_get_global_options()->id)
     , m_shutdown(false)
+    , m_state(MXS_MONITOR_STOPPED)
     , m_master_gtid_domain(GTID_DOMAIN_UNKNOWN)
     , m_external_master_port(PORT_UNKNOWN)
     , m_cluster_modified(true)
@@ -66,6 +67,11 @@ MariaDBMonitor::~MariaDBMonitor()
     clear_server_info();
 }
 
+int32_t MariaDBMonitor::state() const
+{
+    return m_state;
+}
+
 /**
  * Reset and initialize server arrays and related data.
  */

server/modules/monitor/mariadbmon/mariadbmon.hh

@@ -44,6 +44,32 @@ public:
 
     ~MariaDBMonitor();
 
+    /**
+     * @brief Current state of the monitor.
+     *
+     * Note that in principle the state of the monitor may already have
+     * changed when the current state is returned. The state can be fully
+     * trusted only if it is asked in a context when it is know nobody else
+     * can affect it.
+     *
+     * @return @c MXS_MONITOR_RUNNING if the monitor is running,
+     *         @c MXS_MONITOR_STOPPING if the monitor is stopping, and
+     *         @c MXS_MONITOR_STOPPED of the monitor is stopped.
+     */
+    int32_t state() const;
+
+    /**
+     * @brief Find out whether the monitor is running.
+     *
+     * @return True, if the monitor is running, false otherwise.
+     *
+     * @see state().
+     */
+    bool is_running() const
+    {
+        return state() == MXS_MONITOR_RUNNING;
+    }
+
     /**
      * Print diagnostics.
      *