Joseph Doherty
88 lines
3.4 KiB
C#
88 lines
3.4 KiB
C#
using Microsoft.Extensions.Hosting;
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using Microsoft.Extensions.Logging;
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using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Scripting;
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using ZB.MOM.WW.ScadaBridge.Commons.Messages.Scripting;
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namespace ZB.MOM.WW.ScadaBridge.InboundAPI;
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/// <summary>
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/// N1 (arch-review 06 round 2): the Inbound API consumer of the script-artifact
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/// invalidation contract (docs/plans/2026-07-08-script-artifact-invalidation-contract.md,
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/// handoff item (a)). Subscribes to <see cref="IScriptArtifactChangeBus"/> on host
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/// start and, for every <c>ApiMethod</c> notification (e.g. a Transport bundle
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/// import overwriting method scripts, published post-commit), drops the compiled
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/// handler AND the known-bad record via
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/// <see cref="InboundScriptExecutor.InvalidateMethod"/>, so the next request
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/// recompiles from the fresh row without waiting for the per-request
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/// revision-check self-heal.
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/// <para>
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/// Fast-path only: the revision check in <c>ExecuteAsync</c> remains the
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/// correctness fallback — this bus is in-process/per-node and at-least-once
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/// (contract §4), so a missed or duplicate notification must always be harmless.
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/// The bus is optional (site roles and plain test hosts register none) — the
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/// subscriber then no-ops. SharedScript/Template notifications are ignored: this
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/// executor caches only ApiMethod handlers.
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/// </para>
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/// </summary>
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public sealed class ScriptArtifactChangeSubscriber : IHostedService
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{
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private readonly InboundScriptExecutor _executor;
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private readonly ILogger<ScriptArtifactChangeSubscriber> _logger;
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private readonly IScriptArtifactChangeBus? _bus;
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private IDisposable? _subscription;
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/// <summary>Initializes the subscriber.</summary>
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/// <param name="executor">The compiled-handler cache to invalidate.</param>
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/// <param name="logger">Logger instance.</param>
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/// <param name="bus">The change bus, or null when the host registers none (site roles, tests).</param>
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public ScriptArtifactChangeSubscriber(
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InboundScriptExecutor executor,
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ILogger<ScriptArtifactChangeSubscriber> logger,
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IScriptArtifactChangeBus? bus = null)
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{
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_executor = executor;
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_logger = logger;
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_bus = bus;
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}
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/// <inheritdoc />
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public Task StartAsync(CancellationToken cancellationToken)
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{
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if (_bus is null)
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{
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_logger.LogDebug(
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"No IScriptArtifactChangeBus registered; inbound handler-cache freshness relies on the per-request revision check alone.");
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return Task.CompletedTask;
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}
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_subscription = _bus.Subscribe(OnChanged);
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return Task.CompletedTask;
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}
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/// <inheritdoc />
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public Task StopAsync(CancellationToken cancellationToken)
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{
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_subscription?.Dispose();
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_subscription = null;
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return Task.CompletedTask;
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}
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private void OnChanged(ScriptArtifactsChanged notification)
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{
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if (!string.Equals(
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notification.ArtifactKind, ScriptArtifactKinds.ApiMethod, StringComparison.Ordinal))
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{
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return; // only ApiMethod handlers are cached by this executor
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}
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foreach (var name in notification.Names)
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{
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_executor.InvalidateMethod(name);
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}
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_logger.LogInformation(
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"Invalidated {Count} inbound API method handler(s) after a {Source} script-artifact change.",
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notification.Names.Count, notification.Source);
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}
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}
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