feat(opcuaserver): per-request HistoryRead deadline — hung backends surface BadTimeout (03/S3)

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs

@@ -1816,6 +1816,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         IDictionary<NodeId, NodeState> cache)
     {
         var session = context.OperationContext?.Session;
+        using var deadline = CreateDeadline();
+        var ct = deadline?.Token ?? CancellationToken.None;
         var work = new List<Func<Task>>(nodesToProcess.Count);
         foreach (var handle in nodesToProcess)
         {
@@ -1829,7 +1831,7 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
             work.Add(() => ServeRawPagedAsync(
                 handle, session, nodesToRead, results, errors,
                 details.StartTime, details.EndTime, details.NumValuesPerNode,
-                CancellationToken.None));
+                ct));
         }
 
         RunBounded(work, HistoryReadBatchParallelism);
@@ -1848,6 +1850,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     {
         // OPC UA ProcessingInterval is a Duration in milliseconds — convert once per batch.
         var interval = TimeSpan.FromMilliseconds(details.ProcessingInterval);
+        using var deadline = CreateDeadline();
+        var ct = deadline?.Token ?? CancellationToken.None;
         var work = new List<Func<Task>>(nodesToProcess.Count);
         foreach (var handle in nodesToProcess)
         {
@@ -1873,7 +1877,7 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
                 details.EndTime,
                 interval,
                 agg,
-                token), CancellationToken.None));
+                token), ct));
         }
 
         RunBounded(work, HistoryReadBatchParallelism);
@@ -1892,13 +1896,15 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     {
         // Snapshot the requested timestamps once — the same list is read for every node.
         var timestamps = details.ReqTimes?.ToList() ?? new List<DateTime>();
+        using var deadline = CreateDeadline();
+        var ct = deadline?.Token ?? CancellationToken.None;
         var work = new List<Func<Task>>(nodesToProcess.Count);
         foreach (var handle in nodesToProcess)
         {
             work.Add(() => ServeNodeAsync(handle, results, errors, (source, tagname, token) => source.ReadAtTimeAsync(
                 tagname,
                 timestamps,
-                token), CancellationToken.None));
+                token), ct));
         }
 
         RunBounded(work, HistoryReadBatchParallelism);
@@ -1918,6 +1924,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         // Snapshot the select clauses once — the same filter projects every node's events.
         var selectClauses = details.Filter?.SelectClauses ?? new SimpleAttributeOperandCollection();
 
+        using var deadline = CreateDeadline();
+        var ct = deadline?.Token ?? CancellationToken.None;
         var work = new List<Func<Task>>(nodesToProcess.Count);
         foreach (var handle in nodesToProcess)
         {
@@ -1933,7 +1941,7 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
             }
 
             var sn = sourceName;
-            work.Add(() => ServeEventsAsync(handle, sn, details, selectClauses, results, errors, CancellationToken.None));
+            work.Add(() => ServeEventsAsync(handle, sn, details, selectClauses, results, errors, ct));
         }
 
         RunBounded(work, HistoryReadBatchParallelism);
@@ -2138,6 +2146,17 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         Task.WhenAll(tasks).GetAwaiter().GetResult();
     }
 
+    /// <summary>
+    ///     Create the per-request deadline source for a HistoryRead arm (arch-review 03/S3): a
+    ///     <see cref="CancellationTokenSource"/> that fires after <see cref="HistoryReadDeadline"/>, so a
+    ///     single request can never hold an SDK request thread longer than the deadline regardless of node
+    ///     count. Returns <c>null</c> when the deadline is non-positive (unbounded — the arm then passes
+    ///     <see cref="CancellationToken.None"/>), matching the <c>ServerHistorianOptions</c> warning.
+    /// </summary>
+    /// <returns>The deadline source, or <c>null</c> for an unbounded (non-positive) deadline.</returns>
+    private CancellationTokenSource? CreateDeadline() =>
+        HistoryReadDeadline > TimeSpan.Zero ? new CancellationTokenSource(HistoryReadDeadline) : null;
+
     /// <summary>Awaits one work item under a semaphore permit, releasing it when the item completes.</summary>
     /// <param name="gate">The concurrency-limiting semaphore.</param>
     /// <param name="work">The per-node work item.</param>