stabilizaiton work - projects rework for maintenanceability and ui livening

src/__Libraries/StellaOps.Provcache/Invalidation/FeedEpochInvalidator.Processing.cs

@@ -0,0 +1,82 @@
+using Microsoft.Extensions.Logging;
+using StellaOps.Messaging;
+using StellaOps.Provcache.Events;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Provcache.Invalidation;
+
+public sealed partial class FeedEpochInvalidator
+{
+    private async Task ProcessEventsAsync(CancellationToken cancellationToken)
+    {
+        try
+        {
+            // Start from latest events.
+            await foreach (var streamEvent in _eventStream.SubscribeAsync(StreamPosition.End, cancellationToken))
+            {
+                try
+                {
+                    await HandleEventAsync(streamEvent.Event, cancellationToken);
+                    Interlocked.Increment(ref _eventsProcessed);
+                    _lastEventAt = _timeProvider.GetUtcNow();
+                }
+                catch (Exception ex)
+                {
+                    Interlocked.Increment(ref _errors);
+                    _logger.LogError(
+                        ex,
+                        "Error processing FeedEpochAdvancedEvent {EventId} for feed {FeedId}",
+                        streamEvent.Event.EventId,
+                        streamEvent.Event.FeedId);
+                }
+            }
+        }
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+        {
+            // Normal shutdown.
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Fatal error in FeedEpochInvalidator event processing loop");
+            throw;
+        }
+    }
+
+    private async Task HandleEventAsync(FeedEpochAdvancedEvent @event, CancellationToken cancellationToken)
+    {
+        _logger.LogInformation(
+            "Processing feed epoch advancement: FeedId={FeedId}, PreviousEpoch={PreviousEpoch}, NewEpoch={NewEpoch}",
+            @event.FeedId,
+            @event.PreviousEpoch,
+            @event.NewEpoch);
+
+        // Invalidate entries with feed_epoch older than the new epoch.
+        // The feed_epoch in cache entries is formatted as "feed:epoch" (e.g., "cve:2024-12-24T12:00:00Z").
+        var request = InvalidationRequest.ByFeedEpochOlderThan(
+            @event.NewEpoch,
+            $"Feed {FormatFeedEpoch(@event.FeedId, @event.NewEpoch)} advanced");
+
+        var result = await _provcacheService.InvalidateByAsync(request, cancellationToken);
+
+        Interlocked.Add(ref _entriesInvalidated, result.EntriesAffected);
+
+        _logger.LogInformation(
+            "Feed epoch advancement invalidated {Count} cache entries for feed {FeedId} epoch {NewEpoch}",
+            result.EntriesAffected,
+            @event.FeedId,
+            @event.NewEpoch);
+
+        // Record telemetry.
+        ProvcacheTelemetry.RecordInvalidation("feed_epoch", result.EntriesAffected);
+    }
+
+    /// <summary>
+    /// Formats a feed epoch identifier.
+    /// </summary>
+    private static string FormatFeedEpoch(string feedId, string epoch)
+    {
+        return $"{feedId}:{epoch}";
+    }
+}