perf(deploy): flatten-session caching, bulk DeploySiteAsync, paged management queries

src/ZB.MOM.WW.ScadaBridge.Commons/Interfaces/Services/ITemplateGraphWatermark.cs

@@ -0,0 +1,82 @@
+namespace ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
+
+/// <summary>
+/// Process-wide monotonic version watermark over the template/instance
+/// configuration graph.
+///
+/// <para>
+/// Every mutation that lands through the configuration database bumps the
+/// version of the affected template (or instance), plus a global counter and —
+/// for edge-shaped changes (template added/removed, parent or composition edge
+/// changed) — a separate <see cref="StructureVersion"/>. Consumers use the
+/// watermark two ways:
+/// </para>
+/// <list type="bullet">
+///   <item>
+///     as the discriminator in a flatten-session cache key
+///     (<c>templateId + version</c>), so a memoised template chain can never be
+///     served after that template changed; and
+///   </item>
+///   <item>
+///     as a staleness fast path — when neither the instance nor any template in
+///     its chain has moved since a previously computed revision hash, the hash
+///     is still current and a full re-flatten can be skipped.
+///   </item>
+/// </list>
+///
+/// <para>
+/// Versions are in-memory and process-local. They are deliberately NOT
+/// persisted: a restart (or the standby central node) simply starts from zero,
+/// which invalidates every cached entry and falls back to the authoritative
+/// full flatten. The watermark is therefore only ever able to cause EXTRA work,
+/// never stale work — a correctness property that matters because the value is
+/// not replicated between the two central nodes.
+/// </para>
+/// </summary>
+public interface ITemplateGraphWatermark
+{
+    /// <summary>
+    /// Monotonic counter bumped on every template- or instance-graph mutation.
+    /// Useful as a coarse "did anything change at all" gate.
+    /// </summary>
+    long Global { get; }
+
+    /// <summary>
+    /// Monotonic counter bumped only when the SHAPE of the graph changes — a
+    /// template row added or removed, a parent-template edge changed, or a
+    /// composition row added/removed/repointed. A cached template-chain
+    /// MEMBERSHIP is valid only while this value is unchanged; the per-template
+    /// versions then cover the contents of each member.
+    /// </summary>
+    long StructureVersion { get; }
+
+    /// <summary>Current version of a single template. Zero when never mutated in this process.</summary>
+    /// <param name="templateId">Template id to read.</param>
+    /// <returns>The template's monotonic version.</returns>
+    long GetTemplateVersion(int templateId);
+
+    /// <summary>Current version of a single instance (its override/binding rows). Zero when never mutated in this process.</summary>
+    /// <param name="instanceId">Instance id to read.</param>
+    /// <returns>The instance's monotonic version.</returns>
+    long GetInstanceVersion(int instanceId);
+
+    /// <summary>Records a mutation of the given template.</summary>
+    /// <param name="templateId">Template whose version is bumped.</param>
+    /// <param name="structural">
+    /// When <c>true</c> the change altered the graph shape (add/remove/parent or
+    /// composition edge) and <see cref="StructureVersion"/> is bumped too.
+    /// </param>
+    void BumpTemplate(int templateId, bool structural = false);
+
+    /// <summary>Records a mutation of the given instance.</summary>
+    /// <param name="instanceId">Instance whose version is bumped.</param>
+    void BumpInstance(int instanceId);
+
+    /// <summary>
+    /// Records a mutation whose affected template/instance could not be
+    /// attributed to a specific id. Bumps <see cref="Global"/> and
+    /// <see cref="StructureVersion"/>, invalidating every chain-membership and
+    /// staleness fast path — the safe, conservative fallback.
+    /// </summary>
+    void BumpAll();
+}