[2833] update/clarify the (new) meaning of DATASRC_LIST_NOT_CACHED

it now doesn't log it for each zone but only warns about the entire data
source.

src/lib/datasrc/client_list.cc

@@ -118,13 +118,12 @@ ConfigurableClientList::configure(const ConstElementPtr& config,
             }
 
             // Create a client for the underling data source via factory.
-            // (If it's our internal type of data source, this is essentially
-            // no-op).
+            // If it's our internal type of data source, this is essentially
+            // no-op.  In the latter case, it's of no use unless cache is
+            // allowed; we simply skip building it in that case.
             const DataSourcePair dsrc_pair = getDataSourceClient(type,
                                                                  paramConf);
             if (!allow_cache && !dsrc_pair.first) {
-                // We're not going to load these zones. Issue warnings about
-                // it.
                 LOG_WARN(logger, DATASRC_LIST_NOT_CACHED).
                     arg(name).arg(rrclass_);
                 continue;

src/lib/datasrc/datasrc_messages.mes

@@ -321,12 +321,12 @@ not contain RRs the requested type.  AN NXRRSET indication is returned.
 A debug message indicating that a query for the given name and RR type is being
 processed.
 
-% DATASRC_LIST_NOT_CACHED zone %1/%2 not cached, cache disabled globally. Will not be available.
-The process disabled caching of RR data completely. However, the given zone
-is provided as a master file and it can be served from memory cache only.
-Therefore, the zone will not be available for this process. If this is
-a problem, you should move the zone to some database backend (sqlite3, for
-example) and use it from there.
+% DATASRC_LIST_NOT_CACHED zones in data source %1 for class %2 not cached, cache disabled globally. Will not be available.
+The process disabled caching of RR data completely. However, this data source
+is provided from a master file and it can be served from memory cache only.
+Therefore, the entire data source will not be available for this process. If
+this is a problem, you should configure the zones of that data source to some
+database backend (sqlite3, for example) and use it from there.
 
 % DATASRC_LOAD_FROM_FILE_ERROR Error loading zone %1: %2
 An error was found in the zone data when it was being loaded from a