feat(batch13): port filestore all-last-seqs and filter-is-all helpers

dotnet/src/ZB.MOM.NatsNet.Server/JetStream/FileStore.cs

@@ -2300,6 +2300,92 @@ public sealed class JetStreamFileStore : IStreamStore, IDisposable
         });
     }
 
+    // Lock should be held by caller.
+    private (ulong[] Seqs, Exception? Error) AllLastSeqsLocked()
+    {
+        if (_state.Msgs == 0 || NoTrackSubjects() || _psim == null)
+            return (Array.Empty<ulong>(), null);
+
+        var numSubjects = _psim.Size();
+        if (numSubjects == 0)
+            return (Array.Empty<ulong>(), null);
+
+        var seqs = new List<ulong>(numSubjects);
+        var seen = new HashSet<string>(numSubjects, StringComparer.Ordinal);
+
+        for (var i = _blks.Count - 1; i >= 0; i--)
+        {
+            if (seen.Count == numSubjects)
+                break;
+
+            var mb = _blks[i];
+            if (mb.Fss == null)
+                continue;
+
+            mb.Fss.IterFast((subjectBytes, ss) =>
+            {
+                var subject = Encoding.UTF8.GetString(subjectBytes);
+                if (!seen.Add(subject))
+                    return true;
+
+                if (ss.LastNeedsUpdate)
+                    RecalculateLastForSubject(subject, ss);
+
+                seqs.Add(ss.Last);
+                return true;
+            });
+        }
+
+        seqs.Sort();
+        return (seqs.ToArray(), null);
+    }
+
+    // Lock should be held by caller.
+    private bool FilterIsAll(string[] filters)
+    {
+        ArgumentNullException.ThrowIfNull(filters);
+
+        var streamSubjects = _cfg.Config.Subjects ?? [];
+        if (filters.Length != streamSubjects.Length)
+            return false;
+
+        var sortedFilters = filters.ToArray();
+        var sortedSubjects = streamSubjects.ToArray();
+        Array.Sort(sortedFilters, StringComparer.Ordinal);
+        Array.Sort(sortedSubjects, StringComparer.Ordinal);
+
+        for (var i = 0; i < sortedFilters.Length; i++)
+        {
+            if (!SubscriptionIndex.SubjectIsSubsetMatch(sortedSubjects[i], sortedFilters[i]))
+                return false;
+        }
+
+        return true;
+    }
+
+    // Lock should be held by caller.
+    private void RecalculateLastForSubject(string subject, SimpleState ss)
+    {
+        var subjectBytes = Encoding.UTF8.GetBytes(subject);
+        for (var i = _blks.Count - 1; i >= 0; i--)
+        {
+            var fss = _blks[i].Fss;
+            if (fss == null)
+                continue;
+
+            var (candidate, ok) = fss.Find(subjectBytes);
+            if (!ok || candidate == null || candidate.Last == 0)
+                continue;
+
+            ss.Last = candidate.Last;
+            ss.LastNeedsUpdate = false;
+            return;
+        }
+
+        ss.Last = 0;
+        ss.LastNeedsUpdate = false;
+    }
+
     // -----------------------------------------------------------------------
     // IStreamStore — type / state
     // -----------------------------------------------------------------------