Replace FIXME with rationale for not cleaning expired delegdb nodes

Expired delegation nodes are naturally replaced when the resolver
fetches fresh data, and any remaining stale nodes are reclaimed by
SIEVE eviction under memory pressure.

diff --git a/lib/dns/deleg.c b/lib/dns/deleg.c
index 151d7fe8ba9acbee4a619806f4a24028f58cb5c8..92ee3f1a8f109f78e10139d2d1a3ccafc1474463 100644 (file)
--- a/lib/dns/deleg.c
+++ b/lib/dns/deleg.c
@@ -339,9 +339,11 @@ dns__deleg_lookup(dns_delegdb_t *delegdb, dns_qpread_t *qpr,
        }
 
        /*
-        * FIXME: if we lookup something that has expired, we need
-        * either the "deadnodes" (see qpcache) mechanism here - or call
-        * something like isc_async_run(delete_me, node).
+        * The expired node will be replaced when the resolver fetches
+        * a fresh delegation, so there is no need to schedule explicit
+        * cleanup here.  Stale nodes that are never replaced will
+        * eventually be evicted by the SIEVE policy under memory
+        * pressure.
         */
        return ISC_R_NOTFOUND;
 }