Add more error messages to monitors

When the execution of a query fails, the error reported by the Connector-C
and the server where the query was executed is logged.

include/maxscale/monitor.h

@@ -243,4 +243,11 @@ void mon_process_state_changes(MXS_MONITOR *monitor, const char *script, uint64_
  */
 void mon_hangup_failed_servers(MXS_MONITOR *monitor);
 
+/**
+ * @brief Report query errors
+ *
+ * @param db Database where the query failed
+ */
+void mon_report_query_error(MXS_MONITOR_SERVERS* db);
+
 MXS_END_DECLS

server/core/monitor.c

@@ -1430,6 +1430,14 @@ void mon_hangup_failed_servers(MXS_MONITOR *monitor)
         }
     }
 }
+
+void mon_report_query_error(MXS_MONITOR_SERVERS* db)
+{
+    MXS_ERROR("Failed to execute query on server '%s' ([%s]:%d): %s",
+              db->server->unique_name, db->server->name,
+              db->server->port, mysql_error(db->con));
+}
+
 /**
   * Acquire locks on all servers monitored by this monitor. There should
   * only be max 1 monitor per server.

server/modules/monitor/auroramon/auroramon.c

@@ -79,10 +79,7 @@ void update_server_status(MXS_MONITOR *monitor, MXS_MONITOR_SERVERS *database)
             }
             else
             {
-                MXS_ERROR("Failed to query server %s ([%s]:%d): %d, %s",
+                mon_report_query_error(database);
-                          database->server->unique_name, database->server->name,
-                          database->server->port, mysql_errno(database->con),
-                          mysql_error(database->con));
             }
         }
         else

server/modules/monitor/galeramon/galeramon.c

@@ -311,10 +311,18 @@ monitorDatabase(MXS_MONITOR *mon, MXS_MONITOR_SERVERS *database)
                     }
                     mysql_free_result(result2);
                 }
+                else
+                {
+                    mon_report_query_error(database);
+                }
             }
         }
         mysql_free_result(result);
     }
+    else
+    {
+        mon_report_query_error(database);
+    }
 
     if (isjoined)
     {
@@ -350,7 +358,10 @@ monitorDatabase(MXS_MONITOR *mon, MXS_MONITOR_SERVERS *database)
             }
             mysql_free_result(result);
         }
-
+        else
+        {
+            mon_report_query_error(database);
+        }
         server_set_status_nolock(&temp_server, SERVER_JOINED);
     }
     else
@@ -786,9 +797,7 @@ static void update_sst_donor_nodes(MXS_MONITOR *mon, int is_cluster)
         }
         else
         {
-            MXS_ERROR("Error while selecting 'wsrep_node_name' from node %s: %s",
+            mon_report_query_error(ptr);
-                      ptr->server->unique_name,
-                      mysql_error(ptr->con));
         }
     }
 

server/modules/monitor/mmmon/mmmon.c

@@ -283,7 +283,10 @@ monitorDatabase(MXS_MONITOR* mon, MXS_MONITOR_SERVERS *database)
         }
         mysql_free_result(result);
     }
-
+    else
+    {
+        mon_report_query_error(database);
+    }
     /* Check if the Slave_SQL_Running and Slave_IO_Running status is
      * set to Yes
      */
@@ -348,6 +351,10 @@ monitorDatabase(MXS_MONITOR* mon, MXS_MONITOR_SERVERS *database)
                 isslave = 0;
             }
         }
+        else
+        {
+            mon_report_query_error(database);
+        }
     }
     else
     {
@@ -409,6 +416,10 @@ monitorDatabase(MXS_MONITOR* mon, MXS_MONITOR_SERVERS *database)
 
             mysql_free_result(result);
         }
+        else
+        {
+            mon_report_query_error(database);
+        }
     }
 
     /* get variable 'read_only' set by an external component */
@@ -436,6 +447,10 @@ monitorDatabase(MXS_MONITOR* mon, MXS_MONITOR_SERVERS *database)
         }
         mysql_free_result(result);
     }
+    else
+    {
+        mon_report_query_error(database);
+    }
 
     /* Remove addition info */
     monitor_clear_pending_status(database, SERVER_STALE_STATUS);

server/modules/monitor/mysqlmon/mysql_mon.c

@@ -492,6 +492,10 @@ static inline void monitor_mysql_db(MXS_MONITOR_SERVERS* database, MYSQL_SERVER_
 
         mysql_free_result(result);
     }
+    else
+    {
+        mon_report_query_error(database);
+    }
 }
 
 /**
@@ -544,7 +548,10 @@ static MXS_MONITOR_SERVERS *build_mysql51_replication_tree(MXS_MONITOR *mon)
 
                 mysql_free_result(result);
             }
-
+            else
+            {
+                mon_report_query_error(database);
+            }
 
             /* Set the Slave Role */
             if (ismaster)
@@ -718,6 +725,10 @@ monitorDatabase(MXS_MONITOR *mon, MXS_MONITOR_SERVERS *database)
         }
         mysql_free_result(result);
     }
+    else
+    {
+        mon_report_query_error(database);
+    }
 
     /* Check first for MariaDB 10.x.x and get status for multi-master replication */
     if (server_version >= 100000)

server/modules/monitor/ndbclustermon/ndbclustermon.c

@@ -245,6 +245,10 @@ monitorDatabase(MXS_MONITOR_SERVERS *database, char *defaultUser, char *defaultP
         }
         mysql_free_result(result);
     }
+    else
+    {
+        mon_report_query_error(database);
+    }
 
     /* Check the the SQL node id in the MySQL cluster */
     if (mysql_query(database->con, "SHOW STATUS LIKE 'Ndb_cluster_node_id'") == 0
@@ -272,6 +276,10 @@ monitorDatabase(MXS_MONITOR_SERVERS *database, char *defaultUser, char *defaultP
         }
         mysql_free_result(result);
     }
+    else
+    {
+        mon_report_query_error(database);
+    }
 
     if (isjoined)
     {