fix search index threading (#141)

* fix search index threading

* code cleanup

ErsatzTV/Services/SchedulerService.cs

@@ -24,6 +24,7 @@ namespace ErsatzTV.Services
         private readonly IEntityLocker _entityLocker;
         private readonly ILogger<SchedulerService> _logger;
         private readonly ChannelWriter<IPlexBackgroundServiceRequest> _plexWorkerChannel;
+        private readonly ChannelWriter<ISearchBackgroundServiceRequest> _searchWorkerChannel;
         private readonly IServiceScopeFactory _serviceScopeFactory;
         private readonly ChannelWriter<IBackgroundServiceRequest> _workerChannel;
 
@@ -31,12 +32,14 @@ namespace ErsatzTV.Services
             IServiceScopeFactory serviceScopeFactory,
             ChannelWriter<IBackgroundServiceRequest> workerChannel,
             ChannelWriter<IPlexBackgroundServiceRequest> plexWorkerChannel,
+            ChannelWriter<ISearchBackgroundServiceRequest> searchWorkerChannel,
             IEntityLocker entityLocker,
             ILogger<SchedulerService> logger)
         {
             _serviceScopeFactory = serviceScopeFactory;
             _workerChannel = workerChannel;
             _plexWorkerChannel = plexWorkerChannel;
+            _searchWorkerChannel = searchWorkerChannel;
             _entityLocker = entityLocker;
             _logger = logger;
         }
@@ -123,6 +126,6 @@ namespace ErsatzTV.Services
         }
 
         private ValueTask RebuildSearchIndex(CancellationToken cancellationToken) =>
-            _workerChannel.WriteAsync(new RebuildSearchIndex(), cancellationToken);
+            _searchWorkerChannel.WriteAsync(new RebuildSearchIndex(), cancellationToken);
     }
 }

ErsatzTV/Services/SearchIndexService.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Threading;
+using System.Threading.Channels;
+using System.Threading.Tasks;
+using ErsatzTV.Application;
+using ErsatzTV.Application.Search.Commands;
+using MediatR;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace ErsatzTV.Services
+{
+    public class SearchIndexService : BackgroundService
+    {
+        private readonly ChannelReader<ISearchBackgroundServiceRequest> _channel;
+        private readonly ILogger<SearchIndexService> _logger;
+        private readonly IServiceScopeFactory _serviceScopeFactory;
+
+        public SearchIndexService(
+            ChannelReader<ISearchBackgroundServiceRequest> channel,
+            IServiceScopeFactory serviceScopeFactory,
+            ILogger<SearchIndexService> logger)
+        {
+            _channel = channel;
+            _serviceScopeFactory = serviceScopeFactory;
+            _logger = logger;
+        }
+
+        protected override async Task ExecuteAsync(CancellationToken cancellationToken)
+        {
+            _logger.LogInformation("Search index service started");
+
+            await foreach (ISearchBackgroundServiceRequest request in _channel.ReadAllAsync(cancellationToken))
+            {
+                try
+                {
+                    using IServiceScope scope = _serviceScopeFactory.CreateScope();
+                    IMediator mediator = scope.ServiceProvider.GetRequiredService<IMediator>();
+
+                    switch (request)
+                    {
+                        case RebuildSearchIndex rebuildSearchIndex:
+                            await mediator.Send(rebuildSearchIndex, cancellationToken);
+                            break;
+                        case AddItemsToSearchIndex addItemsToSearchIndex:
+                            await mediator.Send(addItemsToSearchIndex, cancellationToken);
+                            break;
+                        case RemoveItemsFromSearchIndex removeItemsFromSearchIndex:
+                            await mediator.Send(removeItemsFromSearchIndex, cancellationToken);
+                            break;
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogWarning(ex, "Failed to process search index service request");
+                }
+            }
+        }
+    }
+}