[trac741] Messages for message entry

src/lib/cache/cache_messages.mes

@@ -35,3 +35,5 @@ $NAMESPACE isc::cache
 % CACHE_MESSAGES_UPDATE updating message entry %1/%2/%3
 
 % CACHE_MESSAGES_REMOVE removing old instance of %1/%2/%3 first
+
+% CACHE_ENTRY_MISSING_RRSET missing RRset to generate message for %1

src/lib/cache/message_entry.cc

@@ -64,7 +64,7 @@ static uint32_t MAX_UINT32 = numeric_limits<uint32_t>::max();
 // tunable.  Values of one to three hours have been found to work well
 // and would make sensible a default.  Values exceeding one day have
 // been found to be problematic. (sec 5, RFC2308)
-// The default value is 3 hourse (10800 seconds)
+// The default value is 3 hours (10800 seconds)
 // TODO:Give an option to let user configure
 static uint32_t MAX_NEGATIVE_CACHE_TTL = 10800;
 
@@ -142,6 +142,8 @@ MessageEntry::genMessage(const time_t& time_now,
         // has expired, if it is, return false.
         vector<RRsetEntryPtr> rrset_entry_vec;
         if (false == getRRsetEntries(rrset_entry_vec, time_now)) {
+            LOG_DEBUG(logger, DBG_TRACE_DATA, CACHE_ENTRY_MISSING_RRSET).
+                arg(entry_name_);
             return (false);
         }