up

src/Excititor/StellaOps.Excititor.WebService/Services/MessagingGraphOverlayCache.cs

@@ -0,0 +1,76 @@
+using Microsoft.Extensions.Options;
+using StellaOps.Excititor.WebService.Contracts;
+using StellaOps.Excititor.WebService.Options;
+using StellaOps.Messaging;
+using StellaOps.Messaging.Abstractions;
+
+namespace StellaOps.Excititor.WebService.Services;
+
+/// <summary>
+/// Graph overlay cache backed by <see cref="IDistributedCache{TValue}"/>.
+/// Supports any transport (InMemory, Valkey, PostgreSQL) via factory injection.
+/// </summary>
+internal sealed class MessagingGraphOverlayCache : IGraphOverlayCache
+{
+    private readonly IDistributedCache<GraphOverlayCacheEntry> _cache;
+    private readonly IOptions<GraphOptions> _options;
+    private readonly TimeProvider _timeProvider;
+
+    public MessagingGraphOverlayCache(
+        IDistributedCacheFactory cacheFactory,
+        IOptions<GraphOptions> options,
+        TimeProvider timeProvider)
+    {
+        ArgumentNullException.ThrowIfNull(cacheFactory);
+        _options = options ?? throw new ArgumentNullException(nameof(options));
+        _timeProvider = timeProvider ?? throw new ArgumentNullException(nameof(timeProvider));
+
+        _cache = cacheFactory.Create<GraphOverlayCacheEntry>(new CacheOptions
+        {
+            KeyPrefix = "graph-overlays:",
+        });
+    }
+
+    public async ValueTask<GraphOverlayCacheHit?> TryGetAsync(
+        string tenant,
+        bool includeJustifications,
+        IReadOnlyList<string> orderedPurls,
+        CancellationToken cancellationToken)
+    {
+        var key = BuildKey(tenant, includeJustifications, orderedPurls);
+        var result = await _cache.GetAsync(key, cancellationToken).ConfigureAwait(false);
+
+        if (result.HasValue)
+        {
+            var cached = result.Value;
+            var ageMs = (long)Math.Max(0, (_timeProvider.GetUtcNow() - cached.CachedAt).TotalMilliseconds);
+            return new GraphOverlayCacheHit(cached.Items, ageMs);
+        }
+
+        return null;
+    }
+
+    public async ValueTask SaveAsync(
+        string tenant,
+        bool includeJustifications,
+        IReadOnlyList<string> orderedPurls,
+        IReadOnlyList<GraphOverlayItem> items,
+        DateTimeOffset cachedAt,
+        CancellationToken cancellationToken)
+    {
+        var key = BuildKey(tenant, includeJustifications, orderedPurls);
+        var ttl = TimeSpan.FromSeconds(Math.Max(1, _options.Value.OverlayTtlSeconds));
+        var entry = new GraphOverlayCacheEntry(items.ToList(), cachedAt);
+        var entryOptions = new CacheEntryOptions { TimeToLive = ttl };
+
+        await _cache.SetAsync(key, entry, entryOptions, cancellationToken).ConfigureAwait(false);
+    }
+
+    private static string BuildKey(string tenant, bool includeJustifications, IReadOnlyList<string> orderedPurls)
+        => $"{tenant}:{includeJustifications}:{string.Join('|', orderedPurls)}";
+}
+
+/// <summary>
+/// Cache entry for graph overlays.
+/// </summary>
+internal sealed record GraphOverlayCacheEntry(List<GraphOverlayItem> Items, DateTimeOffset CachedAt);

src/Excititor/StellaOps.Excititor.WebService/StellaOps.Excititor.WebService.csproj

@@ -17,6 +17,7 @@
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="../__Libraries/StellaOps.Excititor.Core/StellaOps.Excititor.Core.csproj" />
+    <ProjectReference Include="../../__Libraries/StellaOps.Messaging/StellaOps.Messaging.csproj" />
     <ProjectReference Include="../__Libraries/StellaOps.Excititor.Storage.Postgres/StellaOps.Excititor.Storage.Postgres.csproj" />
     <ProjectReference Include="../__Libraries/StellaOps.Excititor.Export/StellaOps.Excititor.Export.csproj" />
     <ProjectReference Include="../__Libraries/StellaOps.Excititor.Connectors.Abstractions/StellaOps.Excititor.Connectors.Abstractions.csproj" />