Merge branch 'fix/archreview-crit2-vt-timeout'

src/Server/ZB.MOM.WW.OtOpcUa.Host/Engines/RoslynVirtualTagEvaluator.cs

@@ -1,4 +1,3 @@
-using System.Collections.Concurrent;
 using Microsoft.Extensions.Logging;
 using ZB.MOM.WW.OtOpcUa.Commons.Engines;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
@@ -20,10 +19,13 @@ namespace ZB.MOM.WW.OtOpcUa.Host.Engines;
 /// Cycle detection + cascade ordering live in <see cref="VirtualTagEngine"/>; this adapter
 /// stays single-tag scoped to keep <see cref="VirtualTagActor"/>'s message loop simple.
 /// </summary>
-public sealed class RoslynVirtualTagEvaluator : IVirtualTagEvaluator, IDisposable
+public sealed class RoslynVirtualTagEvaluator : IVirtualTagEvaluator, IScriptCacheOwner, IDisposable
 {
-    private readonly ConcurrentDictionary<string, ScriptEvaluator<VirtualTagContext, object?>> _cache
-        = new(StringComparer.Ordinal);
+    // Purpose-built source-hash-keyed compile cache: Lazy single-compile (no double-compile race) and
+    // Clear()/Dispose() that dispose each evaluator's collectible AssemblyLoadContext. The apply-boundary
+    // Clear() (driven by VirtualTagHostActor via IScriptCacheOwner) is what stops ALCs accreting across
+    // script edits — the raw ConcurrentDictionary this replaced never released them.
+    private readonly CompiledScriptCache<VirtualTagContext, object?> _cache = new();
     private readonly ILogger<RoslynVirtualTagEvaluator> _logger;
     private readonly SerilogLogger _scriptRoot;
     private readonly TimeSpan _runTimeout;
@@ -64,7 +66,7 @@ public sealed class RoslynVirtualTagEvaluator : IVirtualTagEvaluator, IDisposabl
         ScriptEvaluator<VirtualTagContext, object?> evaluator;
         try
         {
-            evaluator = _cache.GetOrAdd(expression, ScriptEvaluator<VirtualTagContext, object?>.Compile);
+            evaluator = _cache.GetOrCompile(expression);
         }
         catch (CompilationErrorException ex)
         {
@@ -98,11 +100,16 @@ public sealed class RoslynVirtualTagEvaluator : IVirtualTagEvaluator, IDisposabl
 
         try
         {
-            using var cts = new CancellationTokenSource(_runTimeout);
-            var raw = evaluator.RunAsync(context, cts.Token).GetAwaiter().GetResult();
+            // Route through TimedScriptEvaluator (Task.Run + WaitAsync): a raw CancellationToken can't
+            // interrupt a CPU-bound/infinite-loop script (Roslyn scripts don't poll it), so the previous
+            // CTS-only path let one runaway script hang this actor forever. WaitAsync returns control when
+            // the wall-clock budget fires regardless of whether the inner task completes (the orphaned
+            // thread is the documented, accepted trade-off — TimedScriptEvaluator remarks).
+            var timed = new TimedScriptEvaluator<VirtualTagContext, object?>(evaluator, _runTimeout);
+            var raw = timed.RunAsync(context).GetAwaiter().GetResult();
             return VirtualTagEvalResult.Ok(raw);
         }
-        catch (OperationCanceledException)
+        catch (ScriptTimeoutException)
         {
             return VirtualTagEvalResult.Failure($"script timed out after {_runTimeout.TotalSeconds:F1}s");
         }
@@ -113,6 +120,9 @@ public sealed class RoslynVirtualTagEvaluator : IVirtualTagEvaluator, IDisposabl
         }
     }
 
+    /// <inheritdoc />
+    public void ClearCompiledScripts() => _cache.Clear();
+
     private static IReadOnlyDictionary<string, DataValueSnapshot> BuildReadCache(
         IReadOnlyDictionary<string, object?> deps)
     {
@@ -133,10 +143,7 @@ public sealed class RoslynVirtualTagEvaluator : IVirtualTagEvaluator, IDisposabl
     {
         if (_disposed) return;
         _disposed = true;
-        foreach (var ev in _cache.Values)
-        {
-            try { ev.Dispose(); } catch { /* best-effort */ }
-        }
-        _cache.Clear();
+        // CompiledScriptCache.Dispose drains + disposes every materialised evaluator's ALC.
+        _cache.Dispose();
     }
 }

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/VirtualTags/VirtualTagHostActor.cs

@@ -85,6 +85,12 @@ public sealed class VirtualTagHostActor : ReceiveActor
 
     private void OnApply(ApplyVirtualTags msg)
     {
+        // Apply-boundary compile-cache drop: each deploy generation may carry edited script sources, and
+        // the production evaluator roots one collectible AssemblyLoadContext per compiled expression. Drop
+        // them here (mirroring ScriptedAlarmEngine's per-generation clear) so stale ALCs are reclaimed
+        // instead of accreting across edits. No-op for evaluators without a cache (NullVirtualTagEvaluator).
+        (_evaluator as IScriptCacheOwner)?.ClearCompiledScripts();
+
         var desired = new HashSet<string>(msg.Plans.Select(p => p.VirtualTagId), StringComparer.Ordinal);
 
         // Stop + forget children whose vtagId is no longer desired. Stopping the child triggers its