fix: prevent QUIC heartbeat stalls and isolate TCP retransmission counters [CI] [SKIP TESTS]

backend/src/MoShiro.Backend.Analysis/Ops/SessionOps.cs

@@ -9,7 +9,7 @@ internal static class TcpInfoTime
         side is not null && side.Values[row] == 0 ? view.ProbeToUtcMs(ts.Values[row]) : view.AgentToUtcMs(ts.Values[row]);
 }
 
-/// <summary>两次采样之间累计计数的差值（分子）与另一个累计计数的差值（分母），按 side 分别计算。</summary>
+/// <summary>两次采样之间累计计数的差值（分子）与另一个累计计数的差值（分母），按 (side, conn) 分别计算；旧数据没有 conn 时按 side 计算。</summary>
 internal sealed class KernelDeltaOp : MetricOp
 {
     private readonly string _field;
@@ -21,12 +21,13 @@ internal sealed class KernelDeltaOp : MetricOp
         _over = over;
     }
 
-    public override string Signature => $"kernel_delta/{_field}/{_over}/1";
+    public override string Signature => $"kernel_delta/{_field}/{_over}/2";
 
     public override void Evaluate(ChunkView view, RawStream stream, IObservationSink sink)
     {
         RawColumn? ts = stream.Find("ts");
         RawColumn? side = stream.Find("side");
+        RawColumn? connection = stream.Find("conn");
         RawColumn? field = stream.Find(_field);
         RawColumn? over = stream.Find(_over);
         if (ts is null || field is null || over is null)
@@ -34,21 +35,34 @@ internal sealed class KernelDeltaOp : MetricOp
             return;
         }
 
-        var last = new Dictionary<long, (long Field, long Over)>();
+        var last = new Dictionary<(long Side, long Connection), (long Ts, long Field, long Over)>();
         for (int i = 0; i < stream.Count; i++)
         {
-            long key = side?.Values[i] ?? 0;
-            if (last.TryGetValue(key, out (long Field, long Over) previous))
+            if (!ts.IsValid(i) || !field.IsValid(i) || !over.IsValid(i))
             {
-                long dField = Math.Max(0, field.Values[i] - previous.Field);
-                long dOver = Math.Max(0, over.Values[i] - previous.Over);
-                if (dOver > 0)
+                continue;
+            }
+
+            var key = (side?.Values[i] ?? 0, connection?.IsValid(i) == true ? connection.Values[i] : 0);
+            if (last.TryGetValue(key, out (long Ts, long Field, long Over) previous))
+            {
+                // Ignore delayed/duplicate samples without replacing the newer baseline.
+                if (ts.Values[i] <= previous.Ts)
+                {
+                    continue;
+                }
+
+                // Either counter falling means reset/wrap: discard the whole
+                // interval rather than mixing a new numerator with an old denominator.
+                long dField = field.Values[i] - previous.Field;
+                long dOver = over.Values[i] - previous.Over;
+                if (dField >= 0 && dOver > 0)
                 {
                     sink.Emit(TcpInfoTime.ToUtcMs(view, ts, side, i), dField, dOver);
                 }
             }
 
-            last[key] = (field.Values[i], over.Values[i]);
+            last[key] = (ts.Values[i], field.Values[i], over.Values[i]);
         }
     }
 }