feat(deployment): add secure Linux runtime (#17)

src/FinalFactory.Rendezvous.Server/State/InMemoryEphemeralRendezvousStore.cs

@@ -15,6 +15,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
     private readonly Dictionary<MediationHandle, SessionListingId> _presenceHandles = [];
     private readonly Dictionary<MediationHandle, PresenceEntry> _presence = [];
     private readonly Dictionary<JoinAttemptId, AttemptEntry> _attempts = [];
+    private readonly PriorityQueue<AttemptExpiry, long> _attemptExpiries = new();
     private readonly Dictionary<JoinAttemptId, OutcomeReportEntry> _outcomeReports = [];
     private readonly Dictionary<MediationHandle, JoinAttemptId> _attemptHandles = [];
     private readonly Dictionary<string, IdempotencyEntry> _idempotency = new(StringComparer.Ordinal);
@@ -82,6 +83,15 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         }
     }
 
+    internal int GetActiveJoinAttemptCountForDrain()
+    {
+        lock (_gate)
+        {
+            _expiryChurn += RemoveExpiredAttempts(_monotonicClock.Elapsed);
+            return _attempts.Count;
+        }
+    }
+
     internal EphemeralStoreSnapshot GetMetricsSnapshot()
     {
         lock (_gate)
@@ -451,6 +461,9 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             now + _options.JoinAttemptLifetime,
             WallDeadline(now, _options.JoinAttemptLifetime));
         _attempts.Add(command.AttemptId, attempt);
+        _attemptExpiries.Enqueue(
+            new AttemptExpiry(command.AttemptId, attempt.Deadline),
+            attempt.Deadline.Ticks);
         _outcomeReports.Add(command.AttemptId, new(
             command.ListingId,
             command.ClientSubject,
@@ -920,15 +933,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             _presence.Remove(handle);
         }
 
-        JoinAttemptId[] expiredAttempts = _attempts
-            .Where(item => item.Value.Deadline <= now)
-            .Select(static item => item.Key)
-            .ToArray();
-        _expiryChurn += expiredAttempts.Length;
-        foreach (JoinAttemptId attemptId in expiredAttempts)
-        {
-            RemoveAttempt(attemptId);
-        }
+        _expiryChurn += RemoveExpiredAttempts(now);
 
         JoinAttemptId[] expiredOutcomes = _outcomeReports
             .Where(item => item.Value.Deadline <= now)
@@ -958,6 +963,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         _presenceHandles.Clear();
         _presence.Clear();
         _attempts.Clear();
+        _attemptExpiries.Clear();
         _outcomeReports.Clear();
         _attemptHandles.Clear();
         _idempotency.Clear();
@@ -1000,6 +1006,24 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         }
     }
 
+    private int RemoveExpiredAttempts(TimeSpan now)
+    {
+        int removed = 0;
+        while (_attemptExpiries.TryPeek(out AttemptExpiry candidate, out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            _attemptExpiries.Dequeue();
+            if (_attempts.TryGetValue(candidate.AttemptId, out AttemptEntry? current)
+                && current.Deadline == candidate.Deadline)
+            {
+                RemoveAttempt(candidate.AttemptId);
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
     private bool HandleExists(MediationHandle handle) =>
         _presenceHandles.ContainsKey(handle) || _attemptHandles.ContainsKey(handle);
 
@@ -1195,6 +1219,8 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         public bool IsCancelled { get; set; }
     }
 
+    private readonly record struct AttemptExpiry(JoinAttemptId AttemptId, TimeSpan Deadline);
+
     private sealed class OutcomeReportEntry(
         SessionListingId listingId,
         string clientSubject,