Add new parameter type MXS_MODULE_PARAM_SERVERLIST

This is a list of servers, separated by commas. When queried as a
config setting, returns a null-terminated array of SERVER*:s. The
commit includes a serverlist parsing function, which should probably
be used anywhere a similarly formed string is parsed.

include/maxscale/config.h

@@ -205,6 +205,17 @@ struct service* config_get_service(const MXS_CONFIG_PARAMETER *params, const cha
  */
 struct server* config_get_server(const MXS_CONFIG_PARAMETER *params, const char *key);
 
+/**
+ * @brief Get an array of servers. The caller should free the returned array, but not
+ * the array elements.
+ *
+ * @param params List of configuration parameters
+ * @param key Parameter name
+ *
+ * @return Pointer to a null-terminated array of servers, or null if none found.
+ */
+struct server** config_get_serverlist(const MXS_CONFIG_PARAMETER *params, const char *key);
+
 /**
  * @brief Get copy of parameter value if it is defined
  *

include/maxscale/modinfo.h

@@ -79,6 +79,7 @@ enum mxs_module_param_type
     MXS_MODULE_PARAM_PATH, /**< Path to a file or a directory */
     MXS_MODULE_PARAM_SERVICE, /**< Service name */
     MXS_MODULE_PARAM_SERVER, /**< Server name */
+    MXS_MODULE_PARAM_SERVERLIST /**< List of server names, separated by ',' */
 };
 
 /** Maximum and minimum values for integer types */

include/maxscale/server.h

@@ -256,6 +256,7 @@ bool server_remove_parameter(SERVER *server, const char *name);
 
 extern int server_free(SERVER *server);
 extern SERVER *server_find_by_unique_name(const char *name);
+extern SERVER** server_find_by_unique_names(char **server_names, int size);
 extern SERVER *server_find(const char *servname, unsigned short port);
 extern char *server_status(const SERVER *);
 extern void server_clear_set_status(SERVER *server, int specified_bits, int bits_to_set);