partly or unimplemented features - now implemented

src/__Libraries/StellaOps.Provcache/Invalidation/InvalidatorHostedService.cs

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: BUSL-1.1
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using StellaOps.Provcache.Invalidation;
+
+namespace StellaOps.Provcache;
+
+/// <summary>
+/// Hosted service that manages the lifecycle of registered <see cref="IProvcacheInvalidator"/> instances,
+/// starting them on application startup and stopping them on shutdown.
+/// </summary>
+public sealed class InvalidatorHostedService : IHostedService
+{
+    private readonly IReadOnlyList<IProvcacheInvalidator> _invalidators;
+    private readonly ILogger<InvalidatorHostedService> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="InvalidatorHostedService"/> class.
+    /// </summary>
+    /// <param name="invalidators">The registered invalidator instances.</param>
+    /// <param name="logger">The logger.</param>
+    public InvalidatorHostedService(
+        IEnumerable<IProvcacheInvalidator> invalidators,
+        ILogger<InvalidatorHostedService> logger)
+    {
+        ArgumentNullException.ThrowIfNull(invalidators);
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _invalidators = invalidators.ToArray();
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        if (_invalidators.Count == 0)
+        {
+            _logger.LogInformation("No Provcache invalidators registered; skipping startup");
+            return;
+        }
+
+        _logger.LogInformation("Starting {Count} Provcache invalidator(s)", _invalidators.Count);
+
+        foreach (var invalidator in _invalidators)
+        {
+            await invalidator.StartAsync(cancellationToken);
+        }
+
+        _logger.LogInformation("All Provcache invalidators started");
+    }
+
+    public async Task StopAsync(CancellationToken cancellationToken)
+    {
+        if (_invalidators.Count == 0)
+        {
+            return;
+        }
+
+        _logger.LogInformation("Stopping {Count} Provcache invalidator(s)", _invalidators.Count);
+
+        foreach (var invalidator in _invalidators.Reverse())
+        {
+            await invalidator.StopAsync(cancellationToken);
+        }
+
+        _logger.LogInformation("All Provcache invalidators stopped");
+    }
+}

src/__Libraries/StellaOps.Provcache/ProvcacheServiceCollectionExtensions.Invalidation.cs

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: BUSL-1.1
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Hosting;
+using StellaOps.Messaging;
+using StellaOps.Messaging.Abstractions;
+using StellaOps.Provcache.Events;
+using StellaOps.Provcache.Invalidation;
+
+namespace StellaOps.Provcache;
+
+public static partial class ProvcacheServiceCollectionExtensions
+{
+    /// <summary>
+    /// Adds event-driven invalidator services for Provcache.
+    /// </summary>
+    /// <param name="services">The service collection.</param>
+    /// <returns>The service collection for chaining.</returns>
+    public static IServiceCollection AddProvcacheInvalidators(this IServiceCollection services)
+    {
+        ArgumentNullException.ThrowIfNull(services);
+
+        services.TryAddSingleton<IEventStream<SignerRevokedEvent>>(sp =>
+        {
+            var factory = sp.GetRequiredService<IEventStreamFactory>();
+            return factory.Create<SignerRevokedEvent>(new EventStreamOptions
+            {
+                StreamName = SignerRevokedEvent.StreamName
+            });
+        });
+
+        services.TryAddSingleton<IEventStream<FeedEpochAdvancedEvent>>(sp =>
+        {
+            var factory = sp.GetRequiredService<IEventStreamFactory>();
+            return factory.Create<FeedEpochAdvancedEvent>(new EventStreamOptions
+            {
+                StreamName = FeedEpochAdvancedEvent.StreamName
+            });
+        });
+
+        services.TryAddEnumerable(ServiceDescriptor.Singleton<IProvcacheInvalidator, SignerSetInvalidator>());
+        services.TryAddEnumerable(ServiceDescriptor.Singleton<IProvcacheInvalidator, FeedEpochInvalidator>());
+        services.TryAddEnumerable(ServiceDescriptor.Singleton<IHostedService, InvalidatorHostedService>());
+
+        return services;
+    }
+}

src/__Libraries/StellaOps.Provcache/ProvcacheServiceCollectionExtensions.cs

@@ -42,6 +42,7 @@ public static partial class ProvcacheServiceCollectionExtensions
         services.AddSingleton<IWriteBehindQueue, WriteBehindQueue>();
         services.AddHostedService<WriteBehindQueueHostedService>();
         services.AddHttpClient(HttpChunkFetcher.HttpClientName);
+        services.AddProvcacheInvalidators();
 
         return services;
     }
@@ -76,6 +77,7 @@ public static partial class ProvcacheServiceCollectionExtensions
         services.AddSingleton<IWriteBehindQueue, WriteBehindQueue>();
         services.AddHostedService<WriteBehindQueueHostedService>();
         services.AddHttpClient(HttpChunkFetcher.HttpClientName);
+        services.AddProvcacheInvalidators();
 
         return services;
     }