improve caching for static rendering

Oqtane.Server/Extensions/CacheExtensions.cs

@@ -0,0 +1,79 @@
+using Microsoft.Extensions.Caching.Memory;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Oqtane.Extensions
+{
+    public static class CacheExtensions
+    {
+        private static string _cachekeys = "cachekeys";
+
+        public static TItem GetOrCreate<TItem>(this IMemoryCache cache, string key, Func<ICacheEntry, TItem> factory, bool track)
+        {
+            if (!cache.TryGetValue(key, out object result))
+            {
+                using ICacheEntry entry = cache.CreateEntry(key);
+                result = factory(entry);
+                entry.Value = result;
+
+                if (track)
+                {
+                    // track the cache key
+                    List<string> cachekeys;
+                    if (!cache.TryGetValue(_cachekeys, out cachekeys))
+                    {
+                        cachekeys = new List<string>();
+                    }
+                    if (!cachekeys.Contains(key))
+                    {
+                        cachekeys.Add(key);
+                        cache.Set(_cachekeys, cachekeys, new MemoryCacheEntryOptions { Priority = CacheItemPriority.NeverRemove });
+                    }
+                }
+            }
+
+            return (TItem)result;
+        }
+
+        public static void Remove(this IMemoryCache cache, string key, bool track)
+        {
+            List<string> cachekeys;
+
+            if (track && key.EndsWith("*"))
+            {
+                // wildcard cache key removal
+                var prefix = key.Substring(0, key.Length - 1);
+                if (cache.TryGetValue(_cachekeys, out cachekeys) && cachekeys.Any())
+                {
+                    for (var i = cachekeys.Count - 1; i >= 0; i--)
+                    {
+                        if (cachekeys[i].StartsWith(prefix))
+                        {
+                            cache.Remove(cachekeys[i]);
+                            cachekeys.RemoveAt(i);
+                        }
+                    }
+                    cache.Set(_cachekeys, cachekeys, new MemoryCacheEntryOptions { Priority = CacheItemPriority.NeverRemove });
+                }
+            }
+            else
+            {
+                cache.Remove(key);
+            }
+
+            // reconcile all tracked cache keys
+            if (track && cache.TryGetValue(_cachekeys, out cachekeys) && cachekeys.Any())
+            {
+                for (var i = cachekeys.Count - 1; i >= 0; i--)
+                {
+                    if (!cache.TryGetValue(cachekeys[i], out _))
+                    {
+                        cachekeys.RemoveAt(i);
+                    }
+                }
+                cache.Set(_cachekeys, cachekeys, new MemoryCacheEntryOptions { Priority = CacheItemPriority.NeverRemove });
+            }
+        }
+    }
+}