propagate shared-config and library-option changes between instances

Add a Redis pub/sub invalidation bus, publish from the configuration and library-option write paths, and drop the matching local cache entry on the instances that did not write. No-op without a Redis connection string, and fails open when it is unreachable.
2026-09-20 23:47:21 +10:00
parent ec581b5e5f
commit b662ffa48f
16 changed files with 919 additions and 1 deletions
@@ -0,0 +1,77 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MediaBrowser.Common.Configuration;
+using MediaBrowser.Controller.Entities;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Emby.Server.Implementations.Configuration
+{
+    /// <summary>
+    /// Applies the configuration invalidations published by the other instances sharing this
+    /// configuration directory, dropping the local cache entry so the next read comes off the shared file.
+    /// </summary>
+    public sealed class ConfigurationInvalidationSubscriber : IHostedService
+    {
+        private readonly IConfigurationInvalidationBus _bus;
+        private readonly IConfigurationManager _configurationManager;
+        private readonly ILogger<ConfigurationInvalidationSubscriber> _logger;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ConfigurationInvalidationSubscriber"/> class.
+        /// </summary>
+        /// <param name="bus">The invalidation bus.</param>
+        /// <param name="configurationManager">The configuration manager holding the cached configuration.</param>
+        /// <param name="logger">The logger.</param>
+        public ConfigurationInvalidationSubscriber(
+            IConfigurationInvalidationBus bus,
+            IConfigurationManager configurationManager,
+            ILogger<ConfigurationInvalidationSubscriber> logger)
+        {
+            _bus = bus;
+            _configurationManager = configurationManager;
+            _logger = logger;
+        }
+
+        /// <inheritdoc />
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            _bus.Subscribe(Apply);
+            return Task.CompletedTask;
+        }
+
+        /// <inheritdoc />
+        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
+        private void Apply(ConfigurationInvalidation invalidation)
+        {
+            try
+            {
+                switch (invalidation.Scope)
+                {
+                    case ConfigurationInvalidationScope.SystemConfiguration:
+                        _configurationManager.InvalidateCachedConfiguration(null);
+                        break;
+                    case ConfigurationInvalidationScope.NamedConfiguration when !string.IsNullOrEmpty(invalidation.Target):
+                        _configurationManager.InvalidateCachedConfiguration(invalidation.Target);
+                        break;
+                    case ConfigurationInvalidationScope.LibraryOptions when !string.IsNullOrEmpty(invalidation.Target):
+                        CollectionFolder.InvalidateLibraryOptions(invalidation.Target);
+                        break;
+                    case ConfigurationInvalidationScope.AllLibraryOptions:
+                        CollectionFolder.InvalidateAllLibraryOptions();
+                        break;
+                    default:
+                        return;
+                }
+
+                _logger.LogDebug("Applied {Scope} invalidation for {Target} from {OriginId}.", invalidation.Scope, invalidation.Target, invalidation.OriginId);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Failed to apply a {Scope} invalidation for {Target}.", invalidation.Scope, invalidation.Target);
+            }
+        }
+    }
+}