resolves #4899: output cache for sitemap

Oqtane.Server/Services/CacheService.cs

@@ -0,0 +1,41 @@
+using System.Threading;
+using System.Threading.Tasks;
+
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.OutputCaching;
+
+using Oqtane.Documentation;
+using Oqtane.Enums;
+using Oqtane.Infrastructure;
+using Oqtane.Shared;
+
+namespace Oqtane.Services
+{
+    [PrivateApi("Don't show in the documentation, as everything should use the Interface")]
+    public class ServerCacheService : ICacheService
+    {
+        private readonly IOutputCacheStore _outputCacheStore;
+        private readonly ILogManager _logger;
+        private readonly IHttpContextAccessor _accessor;
+
+        public ServerCacheService(IOutputCacheStore outputCacheStore, ILogManager logger, IHttpContextAccessor accessor)
+        {
+            _outputCacheStore = outputCacheStore;
+            _logger = logger;
+            _accessor = accessor;
+        }
+
+        public async Task EvictOutputCacheByTag(string tag, CancellationToken cancellationToken = default)
+        {
+            if (_accessor.HttpContext.User.IsInRole(RoleNames.Admin))
+            {
+                await _outputCacheStore.EvictByTagAsync(tag, cancellationToken);
+                _logger.Log(LogLevel.Information, this, LogFunction.Other, "Evicted Output Cache for Tag {Tag}", tag);
+            }
+            else
+            {
+                _logger.Log(LogLevel.Error, this, LogFunction.Security, "Unauthorized Output Cache Eviction for {Tag}", tag);
+            }
+        }
+    }
+}