fix(quic): exclude locally rejected datagrams [CI]

backend/probe/src/MoShiro.Probe/Link/AgentConnection.cs

@@ -51,7 +51,7 @@ public sealed class AgentConnection : IDisposable
 
     public KnownAgent Endpoint { get; }
 
-    public bool IsConnected => _session is not null;
+    public bool IsConnected => _session is not null && Volatile.Read(ref _activeDatagrams)?.IsConnected == true;
 
     public int RoleCount => _session?.RoleCount ?? 0;
 
@@ -91,16 +91,26 @@ public sealed class AgentConnection : IDisposable
                 p95 = sorted[(int)Math.Ceiling(sorted.Length * 0.95) - 1];
             }
 
-            QuicTransportSnapshot? transport = Volatile.Read(ref _activeDatagrams)?.GetTransportSnapshot();
+            QuicDatagramTransport? datagrams = Volatile.Read(ref _activeDatagrams);
+            bool connected = _session is not null && datagrams?.IsConnected == true;
+            ProbeLinkAttemptState state = _attemptState;
+            string? lastError = _lastError;
+            if (!connected && state == ProbeLinkAttemptState.Connected)
+            {
+                state = ProbeLinkAttemptState.RetryWait;
+                lastError ??= "QUIC datagram transport is closed; reconnecting";
+            }
+
+            QuicTransportSnapshot? transport = datagrams?.GetTransportSnapshot();
             return new ProbeQuicLinkHealth
             {
                 AgentId = Endpoint.AgentId,
                 IpVersion = Endpoint.IpVersion,
-                Connected = IsConnected,
+                Connected = connected,
-                State = _attemptState,
+                State = state,
-                LastError = _lastError,
+                LastError = lastError,
                 RetryAttempt = _lastRetryAttempt,
-                RetryInMs = _attemptState == ProbeLinkAttemptState.RetryWait && _retryAt is { } retryAt
+                RetryInMs = state == ProbeLinkAttemptState.RetryWait && _retryAt is { } retryAt
                     ? Math.Max(0, (long)(retryAt - _env.Time.GetUtcNow()).TotalMilliseconds)
                     : null,
                 HandshakeAttempts = _handshakeAttempts,
@@ -282,9 +292,21 @@ public sealed class AgentConnection : IDisposable
             _env.Log.Info("agent session up", ("agent", Endpoint.AgentId), ("offset_us", clock.OffsetUs));
             Task maintenance = MaintainAsync(rpc, session, clock, cts.Token);
             Task finished = await Task.WhenAny(run, receive, pump, maintenance);
+            string reason = finished == run
+                ? "closed by the Agent control connection"
+                : finished == receive
+                    ? "QUIC datagram transport closed"
+                    : finished == pump
+                        ? "Probe outbox pump stopped"
+                        : "connection maintenance stopped";
+            if (finished.IsFaulted && finished.Exception?.GetBaseException() is { } error)
+            {
+                reason = $"{error.GetType().Name}: {error.Message}";
+            }
+
             await cts.CancelAsync();
             await Task.WhenAll(Quiet(run), Quiet(receive), Quiet(pump), Quiet(maintenance));
-            return finished == run ? "closed by the agent" : "session task failed";
+            return reason;
         }
         finally
         {

backend/shared/MoShiro.Measurement/Blocks/Echo.cs

@@ -1,5 +1,6 @@
 using System.Net;
 using System.Net.Sockets;
+using Fleet.Core;
 using MoShiro.Protocol;
 
 namespace MoShiro.Measurement;
@@ -26,6 +27,7 @@ internal sealed class EchoRows
     private readonly int _t4;
     private readonly long _graceUs;
     private readonly bool _settleOnReply;
+    private long _discarded;
 
     public EchoRows(KindSpec kind, int capacity, long graceUs, bool settleOnReply)
     {
@@ -38,7 +40,7 @@ internal sealed class EchoRows
         _t4 = _log.Store.ColumnIndex("t4");
     }
 
-    public long Count => _log.Count;
+    public long Count => _log.Count - Interlocked.Read(ref _discarded);
 
     public uint Add(int size, long t1Us)
     {
@@ -56,6 +58,17 @@ internal sealed class EchoRows
         }
     }
 
+    public bool Discard(uint seq)
+    {
+        if (!_log.Store.Remove(seq))
+        {
+            return false;
+        }
+
+        Interlocked.Increment(ref _discarded);
+        return true;
+    }
+
     public RawStream? Take(long nowUs, bool all) =>
         _log.Take(
             key => (_settleOnReply && _log.Store.IsSet(key, _t4)) || (_log.Store.TryGet(key, _t1, out long t1) && t1 <= nowUs - _graceUs),
@@ -68,6 +81,8 @@ internal sealed class EchoRows
 public sealed class DatagramEchoDialer : BlockBase
 {
     private readonly EchoRows _rows;
+    private readonly object _gate = new();
+    private long _nextSendFailureWarningUs;
 
     public DatagramEchoDialer(BlockEnv env, BlockSpec spec)
         : base(env, spec)
@@ -92,9 +107,21 @@ public sealed class DatagramEchoDialer : BlockBase
             while (await timer.WaitForNextTickAsync(ct))
             {
                 long t1 = Env.Clock.NowUs();
+                lock (_gate)
+                {
                     uint seq = _rows.Add(size, t1);
                     MeasurementDatagram.Write(packet, new MeasurementDatagramHeader(MeasurementDatagramType.EchoRequest, session.SessionId, Spec.StreamId, seq, t1), session.Key);
-                datagrams.Send(session, target, packet);
+                    if (!datagrams.Send(session, target, packet))
+                    {
+                        _rows.Discard(seq);
+                        if (t1 >= _nextSendFailureWarningUs)
+                        {
+                            Env.Log.Warn("QUIC echo datagram was not queued; omitted from loss samples",
+                                ("stream", Spec.StreamId), ("seq", seq), ("bytes", size));
+                            _nextSendFailureWarningUs = t1 + 5_000_000;
+                        }
+                    }
+                }
             }
         }
         catch (OperationCanceledException)
@@ -109,7 +136,12 @@ public sealed class DatagramEchoDialer : BlockBase
 
     public override int Flush(FlushMode mode, long peerProduced = 0)
     {
-        RawStream? stream = _rows.Take(Env.Clock.NowUs(), mode == FlushMode.All);
+        RawStream? stream;
+        lock (_gate)
+        {
+            stream = _rows.Take(Env.Clock.NowUs(), mode == FlushMode.All);
+        }
+
         if (stream is null)
         {
             return 0;
@@ -122,10 +154,13 @@ public sealed class DatagramEchoDialer : BlockBase
     private void OnPacket(in QuicDatagramDelivery delivery)
     {
         if (delivery.Header.Type == MeasurementDatagramType.EchoReply)
+        {
+            lock (_gate)
             {
                 _rows.Reply(delivery.Header.Seq, delivery.ReceiveUs);
             }
         }
+    }
 }
 
 /// <summary>UDP 回显，监听方（Agent）：校验后立即回复一个等长的包，记录 t2（到达）和 t3（回复发出），按序号留给合并。</summary>

backend/shared/MoShiro.Measurement/Blocks/Train.cs

@@ -1,5 +1,6 @@
 using System.Diagnostics;
 using System.Net;
+using Fleet.Core;
 using MoShiro.Protocol;
 
 namespace MoShiro.Measurement;
@@ -121,7 +122,13 @@ public sealed class TrainListener : BlockBase
             {
                 long sendUs = Env.Clock.NowUs();
                 MeasurementDatagram.Write(packet, new MeasurementDatagramHeader(MeasurementDatagramType.Data, session.SessionId, Spec.StreamId, seq, sendUs), session.Key);
-                Env.Datagrams!.Send(session, target, packet);
+                if (!Env.Datagrams!.Send(session, target, packet))
+                {
+                    Env.Log.Warn("QUIC train datagram was not queued; stopping the train without counting it as loss",
+                        ("stream", Spec.StreamId), ("seq", seq), ("bytes", size));
+                    return;
+                }
+
                 Span<long> row = [size, sendUs];
                 _records.SetRow(seq, row);
                 Interlocked.Exchange(ref _sent, seq + 1L);
@@ -171,7 +178,10 @@ public sealed class TrainDialer : BlockBase
             for (uint seq = 0; seq < 3; seq++)
             {
                 MeasurementDatagram.Write(hello, new MeasurementDatagramHeader(MeasurementDatagramType.Data, session.SessionId, Spec.StreamId, seq, Env.Clock.NowUs()), session.Key);
-                datagrams.Send(session, target, hello);
+                if (!datagrams.Send(session, target, hello))
+                {
+                    throw new BlockFaultException($"QUIC datagram send failed during path discovery (seq {seq}).");
+                }
             }
 
             await WaitUntilCancelledAsync(ct);

backend/shared/MoShiro.Measurement/Core/RowStore.cs

@@ -138,6 +138,36 @@ public sealed class RowStore
         }
     }
 
+    /// <summary>Remove a row that was reserved locally but never accepted by the transport.</summary>
+    internal bool Remove(long key)
+    {
+        lock (_gate)
+        {
+            if (key < 0)
+            {
+                return false;
+            }
+
+            int slot = (int)(key % _capacity);
+            if (_keys[slot] != key)
+            {
+                return false;
+            }
+
+            _keys[slot] = -1;
+            for (int i = 0; i < _columns.Count; i++)
+            {
+                _values[i][slot] = 0;
+                if (_valid[i] is { } valid)
+                {
+                    valid[slot] = false;
+                }
+            }
+
+            return true;
+        }
+    }
+
     /// <summary>读一个值；行不存在或该列没有设置（可空列）返回 false。</summary>
     public bool TryGet(long key, int column, out long value)
     {

backend/shared/MoShiro.Measurement/Net/MsQuicConnection.cs

@@ -99,7 +99,7 @@ internal sealed class MsQuicConnection : IAsyncDisposable, IDatagramConnection
         return RemoteEndPoint;
     }
 
-    public bool IsReady => _connected.Task.IsCompletedSuccessfully && Volatile.Read(ref _sendEnabled) != 0;
+    public bool IsReady => Volatile.Read(ref _handle) != 0 && _connected.Task.IsCompletedSuccessfully && Volatile.Read(ref _sendEnabled) != 0;
 
     public int MaxDatagramBytes => Volatile.Read(ref _maxDatagramBytes);
 

backend/shared/MoShiro.Measurement/Net/QuicDatagramTransport.cs

@@ -128,13 +128,16 @@ public sealed class QuicDatagramTransport : IDisposable, IAsyncDisposable
     public void Unregister(uint streamId) => _router.Unregister(streamId);
 
     /// <summary>Sends one measurement datagram on the connection for the supplied session.</summary>
-    public void Send(DataSession session, EndPoint target, ReadOnlySpan<byte> packet)
+    public bool Send(DataSession session, EndPoint target, ReadOnlySpan<byte> packet)
     {
         _ = target; // A QUIC connection owns its path; the Agent learns it from authenticated datagrams.
         if (session.DatagramConnection?.Send(packet) == true)
         {
             _router.Counters.PacketOut();
+            return true;
         }
+
+        return false;
     }
 
     public async Task RunAsync(CancellationToken ct)

backend/shared/tests/MoShiro.Measurement.Tests/MeasurementTests.cs

@@ -307,6 +307,20 @@ public sealed class MeasurementTests
         Assert.Equal([1L], rows.Take(0, all: true)!.Find("seq")!.Values);
     }
 
+    [Fact]
+    public void EchoRows_DiscardedLocalSendIsNotReportedAsNetworkLoss()
+    {
+        var rows = new EchoRows(Kinds.UdpEcho, 64, EchoRows.DatagramGraceUs, settleOnReply: false);
+        uint unsent = rows.Add(64, 0);
+        Assert.True(rows.Discard(unsent));
+
+        uint sent = rows.Add(64, 1_000_000);
+        Assert.Equal(1, rows.Count);
+        RawStream cut = rows.Take(3_500_000, all: false)!;
+        Assert.Equal([(long)sent], cut.Find("seq")!.Values);
+        Assert.Equal([false], cut.Find("t4")!.Valid!);
+    }
+
     // ---- 积木目录 ----
 
     [Fact]