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fix(triggers): bound expression evaluation, align AlarmActor error handling, dedupe config parsing

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This commit is contained in:
Joseph Doherty
2026-05-16 05:43:18 -04:00
parent 41c3fa3d84
commit 78b10d00d8
4 changed files with 80 additions and 45 deletions
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52
src/ScadaLink.SiteRuntime/Actors/AlarmActor.cs
View File

@@ -51,8 +51,8 @@ public class AlarmActor : ReceiveActor
private readonly Script<object?>? _onTriggerCompiledScript;
// Expression trigger: compiled expression + the attribute snapshot it
// evaluates against. The compiled expression is also held on the
// ExpressionEvalConfig; this field caches it for the hot path.
// evaluates against. This field is the single home for the compiled
// expression on the hot path.
private readonly Script<object?>? _compiledTriggerExpression;
private readonly Dictionary<string, object?> _attributeSnapshot = new();
@@ -369,16 +369,38 @@ public class AlarmActor : ReceiveActor
/// Evaluates the compiled trigger expression against the current attribute
/// snapshot, returning the resulting bool. This bool feeds the existing
/// binary Normal↔Active state path — the alarm is active while true. A
/// throwing or non-bool expression is treated as false; the exception
/// propagates to the caller's catch, which logs it and continues.
/// throwing, non-bool, or timed-out expression is treated as false (logged
/// as an alarm error) so that the state machine still runs — an Active
/// alarm correctly clears if the expression starts throwing.
/// </summary>
private bool EvaluateExpression()
{
if (_compiledTriggerExpression == null) return false;
var globals = new TriggerExpressionGlobals(_attributeSnapshot);
var state = _compiledTriggerExpression.RunAsync(globals).GetAwaiter().GetResult();
return state.ReturnValue is bool b && b;
try
{
var globals = new TriggerExpressionGlobals(_attributeSnapshot);
// Bound evaluation with a short timeout. The CancellationToken
// covers cooperative/async cases; a pathological CPU-bound
// expression is not fully interruptible. Acceptable because
// trigger expressions are authored by trusted Design-role users
// and are compile-checked pre-deployment.
using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(2));
var state = _compiledTriggerExpression
.RunAsync(globals, cancellationToken: cts.Token)
.GetAwaiter().GetResult();
return state.ReturnValue is bool b && b;
}
catch (Exception ex)
{
// OperationCanceledException (timeout) falls through here too,
// and is correctly treated as false.
_healthCollector?.IncrementAlarmError();
_logger.LogError(ex,
"Alarm {Alarm} trigger expression evaluation failed on {Instance}; treated as false",
_alarmName, _instanceName);
return false;
}
}
/// <summary>
@@ -518,12 +540,12 @@ public class AlarmActor : ReceiveActor
HiHiMessage: TryReadString(root, "hiHiMessage")),
// Expression triggers have no single monitored attribute; they
// evaluate the compiled expression (passed into the actor) over
// the full attribute snapshot. MonitoredAttributeName is unused.
// evaluate the compiled expression (passed into the actor and
// cached in _compiledTriggerExpression) over the full attribute
// snapshot. MonitoredAttributeName is unused.
AlarmTriggerType.Expression => new ExpressionEvalConfig(
"",
TryReadString(root, "expression") ?? "",
_compiledTriggerExpression),
TriggerExpressionGlobals.ExtractExpression(triggerConfigJson) ?? ""),
_ => new ValueMatchEvalConfig(attr, null)
};
@@ -590,13 +612,13 @@ internal record RateOfChangeEvalConfig(
/// <summary>
/// Expression evaluation config: a read-only boolean C# expression evaluated
/// over the full attribute snapshot. Has no single monitored attribute
/// (<see cref="AlarmEvalConfig.MonitoredAttributeName"/> is empty); the
/// compiled expression is passed into the actor and cached here.
/// (<see cref="AlarmEvalConfig.MonitoredAttributeName"/> is empty). The
/// compiled expression itself lives on the actor's <c>_compiledTriggerExpression</c>
/// field, the single source for the hot path.
/// </summary>
internal record ExpressionEvalConfig(
string MonitoredAttributeName,
string Expression,
Script<object?>? CompiledExpression) : AlarmEvalConfig(MonitoredAttributeName);
string Expression) : AlarmEvalConfig(MonitoredAttributeName);
/// <summary>
/// HiLo evaluation config: any subset of the four setpoints may be set; null

24
src/ScadaLink.SiteRuntime/Actors/InstanceActor.cs
View File

@@ -1,4 +1,5 @@
using Akka.Actor;
using Microsoft.CodeAnalysis.Scripting;
using Microsoft.Extensions.Logging;
using ScadaLink.Commons.Messages.DataConnection;
using ScadaLink.Commons.Messages.DebugView;
@@ -540,7 +541,7 @@ public class InstanceActor : ReceiveActor
// Create Alarm Actors
foreach (var alarm in _configuration.Alarms)
{
Microsoft.CodeAnalysis.Scripting.Script<object?>? onTriggerScript = null;
Script<object?>? onTriggerScript = null;
// Compile on-trigger script if defined
if (!string.IsNullOrEmpty(alarm.OnTriggerScriptCanonicalName))
@@ -599,29 +600,14 @@ public class InstanceActor : ReceiveActor
/// expression, or a compilation failure (logged) — in which case the
/// trigger is inert and the actor still starts.
/// </summary>
private Microsoft.CodeAnalysis.Scripting.Script<object?>? CompileTriggerExpression(
private Script<object?>? CompileTriggerExpression(
string? triggerType, string? triggerConfigJson, string compileName)
{
if (!string.Equals(triggerType, "Expression", StringComparison.OrdinalIgnoreCase))
return null;
if (string.IsNullOrEmpty(triggerConfigJson))
return null;
string? expression;
try
{
var doc = JsonSerializer.Deserialize<JsonElement>(triggerConfigJson);
expression = doc.TryGetProperty("expression", out var e) ? e.GetString() : null;
}
catch (Exception ex)
{
_logger.LogWarning(ex,
"Failed to read trigger expression config for {Name} on {Instance}",
compileName, _instanceUniqueName);
return null;
}
if (string.IsNullOrWhiteSpace(expression))
var expression = TriggerExpressionGlobals.ExtractExpression(triggerConfigJson);
if (expression == null)
return null;
var result = _compilationService.CompileTriggerExpression(compileName, expression);

24
src/ScadaLink.SiteRuntime/Actors/ScriptActor.cs
View File

@@ -210,11 +210,21 @@ public class ScriptActor : ReceiveActor, IWithTimers
try
{
var globals = new TriggerExpressionGlobals(_attributeSnapshot);
var state = _compiledTriggerExpression.RunAsync(globals).GetAwaiter().GetResult();
// Bound evaluation with a short timeout. The CancellationToken
// covers cooperative/async cases; a pathological CPU-bound
// expression is not fully interruptible. Acceptable because
// trigger expressions are authored by trusted Design-role users
// and are compile-checked pre-deployment.
using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(2));
var state = _compiledTriggerExpression
.RunAsync(globals, cancellationToken: cts.Token)
.GetAwaiter().GetResult();
result = state.ReturnValue is bool b && b;
}
catch (Exception ex)
{
// OperationCanceledException (timeout) falls through here too,
// and is correctly treated as false.
LogExpressionError(ex);
result = false;
}
@@ -346,16 +356,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
private static ExpressionTriggerConfig? ParseExpressionTrigger(string? json)
{
if (string.IsNullOrEmpty(json)) return null;
try
{
var doc = JsonDocument.Parse(json);
var expr = doc.RootElement.TryGetProperty("expression", out var e)
? e.GetString()
: null;
return string.IsNullOrWhiteSpace(expr) ? null : new ExpressionTriggerConfig(expr);
}
catch { return null; }
var expr = TriggerExpressionGlobals.ExtractExpression(json);
return expr == null ? null : new ExpressionTriggerConfig(expr);
}
private static IntervalTriggerConfig? ParseIntervalTrigger(string? json)

25
src/ScadaLink.SiteRuntime/Scripts/TriggerExpressionGlobals.cs
View File

@@ -1,3 +1,5 @@
using System.Text.Json;
namespace ScadaLink.SiteRuntime.Scripts;
/// <summary>
@@ -11,6 +13,29 @@ namespace ScadaLink.SiteRuntime.Scripts;
/// </summary>
public sealed class TriggerExpressionGlobals
{
/// <summary>
/// Extracts the <c>"expression"</c> field from an Expression-trigger config
/// JSON document. Returns <c>null</c> for a missing, blank, or malformed
/// config — the single parsing idiom shared by InstanceActor, ScriptActor,
/// and AlarmActor.
/// </summary>
public static string? ExtractExpression(string? triggerConfigJson)
{
if (string.IsNullOrEmpty(triggerConfigJson)) return null;
try
{
using var doc = JsonDocument.Parse(triggerConfigJson);
var expr = doc.RootElement.TryGetProperty("expression", out var e)
? e.GetString()
: null;
return string.IsNullOrWhiteSpace(expr) ? null : expr;
}
catch (JsonException)
{
return null;
}
}
private readonly IReadOnlyDictionary<string, object?> _snapshot;
public TriggerExpressionGlobals(IReadOnlyDictionary<string, object?> snapshot)