docs(acl): fix the two comment nits from the T1 re-review — displacement precision, straggler-test claim

2026-08-17 06:09:13 -04:00
parent 580b77cecf
commit d54b4fab62
2 changed files with 6 additions and 5 deletions
@@ -254,9 +254,9 @@ public sealed class SessionAclDecisionCache
            // paid by every eviction.
            //
            // A shard from a PREVIOUS generation contributes no hint: the fill level it reached belongs to a
-            // set of grants that no longer exists, and it is about to be displaced by the generation check
-            // below in any case. Sizing this generation's storage from the last one's crawl would be a guess
-            // dressed as evidence.
+            // set of grants that no longer exists, and this very Displace replaces it with a fresh shard
+            // stamped to the current generation regardless. Sizing this generation's storage from the last
+            // one's crawl would be a guess dressed as evidence.
            shard = Displace(
                sessionKey, shard, generation,
                capacityHint: shard.Generation == generation
@@ -295,8 +295,9 @@ public sealed class SessionAclDecisionCacheTests
        cache.TryGet(generation: 1, Session, OpcUaOperation.Read, AddressSpaceRealm.Raw, Node, out _)
            .ShouldBeFalse("a superseded snapshot must recompute rather than read the newer generation");

-        // Asserted BEFORE the generation-2 lookup below, which would itself restore a rolled-back stamp and
-        // hide the defect.
+        // Asserted BEFORE the generation-2 lookup below, which would itself restore a rolled-back stamp —
+        // so a stamp assertion made after it could never fail. (The purge half would still surface, as the
+        // last lookup would miss; it is the stamp half that needs its assertion here.)
        cache.Generation.ShouldBe(2, "the straggler must not have rolled the stamp backward");
        cache.Count.ShouldBe(1, "and must not have purged the current generation's entries");