rebuild nucache if serializer changes

src/Umbraco.Web/PublishedCache/NuCache/NuCacheSerializerComponent.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+using System.Configuration;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Umbraco.Core.Composing;
+using Umbraco.Core.Logging;
+using Umbraco.Core.Services;
+
+namespace Umbraco.Web.PublishedCache.NuCache
+{
+    /// <summary>
+    /// Rebuilds the database cache if required when the serializer changes
+    /// </summary>
+    public class NuCacheSerializerComponent : IComponent
+    {
+        private const string Nucache_Serializer_Key = "Umbraco.Web.PublishedCache.NuCache.Serializer";
+        private const string JSON_SERIALIZER_VALUE = "JSON";
+        private readonly IPublishedSnapshotService _service;
+        private readonly IKeyValueService _keyValueService;
+        private readonly IProfilingLogger _profilingLogger;
+
+        public NuCacheSerializerComponent(IPublishedSnapshotService service, IKeyValueService keyValueService,IProfilingLogger profilingLogger)
+        {
+            // service: nothing - this just ensures that the service is created at boot time
+            _service = service;
+            _keyValueService = keyValueService;
+            _profilingLogger = profilingLogger;
+        }
+
+        public void Initialize()
+        {
+            RebuildDatabaseCacheIfSerializerChanged();
+        }
+
+        private void RebuildDatabaseCacheIfSerializerChanged()
+        {
+            var serializer = ConfigurationManager.AppSettings[Nucache_Serializer_Key];
+            var currentSerializer = _keyValueService.GetValue(Nucache_Serializer_Key);
+
+            if (currentSerializer == null)
+            {
+                currentSerializer = JSON_SERIALIZER_VALUE;
+            }
+            if (serializer == null)
+            {
+                serializer = JSON_SERIALIZER_VALUE;
+            }
+
+            if (serializer != currentSerializer)
+            {
+                _profilingLogger.Info<NuCacheSerializerComponent>($"Database NuCache was serialized using {currentSerializer}. Currently configured NuCache serializer {serializer}. Rebuilding Nucache");
+                using (_profilingLogger.TraceDuration<NuCacheSerializerComponent>($"Rebuilding NuCache database with {currentSerializer} serializer"))
+                {
+
+                    _service.Rebuild();
+                    _keyValueService.SetValue(Nucache_Serializer_Key, serializer);
+                }
+            }
+        }
+
+        public void Terminate()
+        { }
+    }
+}

src/Umbraco.Web/PublishedCache/NuCache/NuCacheSerializerComposer.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Umbraco.Core;
+using Umbraco.Core.Composing;
+
+namespace Umbraco.Web.PublishedCache.NuCache
+{
+
+    [ComposeAfter(typeof(NuCacheComposer))]
+    [RuntimeLevel(MinLevel = RuntimeLevel.Run)]
+    public class NuCacheSerializerComposer : ICoreComposer
+    {
+        public void Compose(Composition composition)
+        {
+            composition.Components().Append<NuCacheSerializerComponent>();
+        }
+    }
+}