batch33 task3 implement group B cluster stream features

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

@@ -45,6 +45,9 @@ internal sealed class NatsStream : IDisposable
 
     /// <summary>IRaftNode — stored as object to avoid cross-dependency on Raft session.</summary>
     private object? _node;
+    private StreamAssignment? _assignment;
+    private bool _migrating;
+    private bool _recovering;
 
     public NatsStream(Account account, StreamConfig config, DateTime created)
     {
@@ -79,6 +82,7 @@ internal sealed class NatsStream : IDisposable
         {
             Store = store,
             IsMirror = cfg.Mirror != null,
+            _assignment = sa,
         };
         return stream;
     }
@@ -317,6 +321,97 @@ internal sealed class NatsStream : IDisposable
         finally { _mu.ExitReadLock(); }
     }
 
+    public RaftGroup? RaftGroup()
+    {
+        _mu.EnterReadLock();
+        try { return _assignment?.Group; }
+        finally { _mu.ExitReadLock(); }
+    }
+
+    public IRaftNode? RaftNode()
+    {
+        _mu.EnterReadLock();
+        try { return _node as IRaftNode; }
+        finally { _mu.ExitReadLock(); }
+    }
+
+    public void RemoveNode()
+    {
+        _mu.EnterWriteLock();
+        try
+        {
+            if (_node is IRaftNode raft)
+                raft.Delete();
+            _node = null;
+        }
+        finally
+        {
+            _mu.ExitWriteLock();
+        }
+    }
+
+    public void WaitOnConsumerAssignments(CancellationToken cancellationToken = default)
+    {
+        if (cancellationToken.IsCancellationRequested)
+            return;
+
+        var stopAt = DateTime.UtcNow.AddSeconds(2);
+        while (DateTime.UtcNow < stopAt)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            if (!_recovering)
+                break;
+            Thread.Sleep(50);
+        }
+    }
+
+    public bool IsMigrating()
+    {
+        _mu.EnterReadLock();
+        try { return _migrating; }
+        finally { _mu.ExitReadLock(); }
+    }
+
+    public bool ResetClusteredState(Exception? cause = null)
+    {
+        _mu.EnterWriteLock();
+        try
+        {
+            _recovering = true;
+            _isLeader = false;
+            _leaderTerm = 0;
+            _migrating = false;
+            if (cause != null && _node is IRaftNode raft)
+                raft.StepDown();
+            return true;
+        }
+        finally
+        {
+            _mu.ExitWriteLock();
+        }
+    }
+
+    public bool SkipBatchIfRecovering()
+    {
+        _mu.EnterReadLock();
+        try { return _recovering; }
+        finally { _mu.ExitReadLock(); }
+    }
+
+    public bool ShouldSendLostQuorum()
+    {
+        _mu.EnterReadLock();
+        try
+        {
+            var replicas = Math.Max(1, Config.Replicas);
+            return replicas > 1 && _node is IRaftNode raft && raft.Leaderless();
+        }
+        finally
+        {
+            _mu.ExitReadLock();
+        }
+    }
+
     /// <summary>
     /// Seals the stream so that no new messages can be stored.
     /// Mirrors <c>stream.seal</c> in server/stream.go.