Improve persisted configuration handling

When a persisted configuration file is read, the values in it are
considered to be more up-to-date than the ones in the main configuration
file. This allows all objects to be persisted in a more complete form
making it easier to change configuration values at runtime.

This change is intended to help make runtime alterations to services
possible.

server/core/maxscale/config.h

@@ -92,6 +92,16 @@ bool config_add_param(CONFIG_CONTEXT* obj, const char* key, const char* value);
  */
 bool config_append_param(CONFIG_CONTEXT* obj, const char* key, const char* value);
 
+/**
+ * @brief Replace an existing parameter
+ *
+ * @param obj Configuration context
+ * @param key Parameter name
+ * @param value Parameter value
+ * @return True on success, false on memory allocation error
+ */
+bool config_replace_param(CONFIG_CONTEXT* obj, const char* key, const char* value);
+
 /**
  * @brief Construct an SSL structure
  *

server/core/maxscale/monitor.h

@@ -65,22 +65,6 @@ bool monitorRemoveParameter(MXS_MONITOR *monitor, const char *key);
 void monitorSetInterval (MXS_MONITOR *, unsigned long);
 bool monitorSetNetworkTimeout(MXS_MONITOR *, int, int);
 
-/**
- * @brief Serialize the servers of a monitor to a file
- *
- * This partially converts @c monitor into an INI format file. Only the servers
- * of the monitor are serialized. This allows the monitor to keep monitoring
- * the servers that were added at runtime even after a restart.
- *
- * NOTE: This does not persist the complete monitor configuration and requires
- * that an existing monitor configuration is in the main configuration file.
- * Changes to monitor parameters are not persisted.
- *
- * @param monitor Monitor to serialize
- * @return False if the serialization of the monitor fails, true if it was successful
- */
-bool monitor_serialize_servers(const MXS_MONITOR *monitor);
-
 /**
  * @brief Serialize a monitor to a file
  *

server/core/maxscale/service.h

@@ -82,18 +82,15 @@ void serviceRemoveBackend(SERVICE *service, const SERVER *server);
 /**
  * @brief Serialize a service to a file
  *
- * This partially converts @c service into an INI format file. Only the servers
- * of the service are serialized. This allows the service to keep using the servers
- * added at runtime even after a restart.
+ * This converts @c service into an INI format file.
  *
  * NOTE: This does not persist the complete service configuration and requires
  * that an existing service configuration is in the main configuration file.
- * Changes to service parameters are not persisted.
  *
  * @param service Service to serialize
  * @return False if the serialization of the service fails, true if it was successful
  */
-bool service_serialize_servers(const SERVICE *service);
+bool service_serialize(const SERVICE *service);
 
 /**
  * Internal utility functions