Memory cache extensions

Author: László Jakab

src/AutSoft.Core/Caching/MemoryCacheExtensions.cs

@@ -0,0 +1,121 @@
+using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.Primitives;
+
+namespace AutSoft.Common.Caching;
+
+/// <summary>
+/// Extension functions for <see cref="IMemoryCache"/>
+/// </summary>
+public static class MemoryCacheExtensions
+{
+    private const string Postfix = "CancellationTokenSource";
+
+    /// <summary>
+    /// Get or create a cached element with error handling
+    /// </summary>
+    /// <typeparam name="TItem">The type of the cached element</typeparam>
+    /// <param name="cache">An <see cref="IMemoryCache"/> object</param>
+    /// <param name="key">The key of the cached element</param>
+    /// <param name="factory">The factory method, which can create the element if it isn't cached</param>
+    /// <param name="options">Options of the caching</param>
+    /// <returns>The finded or created element</returns>
+    public static async Task<TItem> GetOrCreateWithErrorHandlingAsync<TItem>(
+        this IMemoryCache cache,
+        string key,
+        Func<ICacheEntry, Task<TItem>> factory,
+        MemoryCacheEntryOptions? options = null)
+    {
+        try
+        {
+            return await cache.GetOrCreateAsync(key, entry =>
+            {
+                entry.SetOptions(options);
+                entry.AddExpirationToken(cache.CreateToken(key));
+                return factory(entry);
+            });
+        }
+        catch
+        {
+            cache.Remove(key);
+            throw;
+        }
+    }
+
+    /// <summary>
+    /// Create or override an element in the cache
+    /// </summary>
+    /// <typeparam name="TItem">The type of the cached element</typeparam>
+    /// <param name="cache">An <see cref="IMemoryCache"/> object</param>
+    /// <param name="key">The key of the cached element</param>
+    /// <param name="value">The cached value</param>
+    /// <param name="size">The size of the cached value</param>
+    /// <param name="options">Options of the caching</param>
+    public static void SetWithErrorHandling<TItem>(
+        this IMemoryCache cache,
+        string key,
+        TItem value,
+        int size,
+        MemoryCacheEntryOptions? options = null)
+    {
+        try
+        {
+            using var entry = cache.CreateEntry(key);
+            entry.Size = size;
+            entry.SetOptions(options);
+            entry.AddExpirationToken(cache.CreateToken(key));
+            entry.Value = value;
+        }
+        catch
+        {
+            cache.Remove(key);
+            throw;
+        }
+    }
+
+    private static void SetOptions(this ICacheEntry entry, MemoryCacheEntryOptions? options = null)
+    {
+        if (options == null)
+        {
+            entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromHours(1);
+            entry.SlidingExpiration = TimeSpan.FromMinutes(10);
+            entry.Priority = CacheItemPriority.Normal;
+        }
+        else
+        {
+            entry.AbsoluteExpirationRelativeToNow = options.AbsoluteExpirationRelativeToNow;
+            entry.SlidingExpiration = options.SlidingExpiration;
+            entry.Priority = options.Priority;
+        }
+    }
+
+    private static IChangeToken CreateToken(this IMemoryCache cache, string key)
+    {
+        var tokenSourceKey = key + Postfix;
+
+        var source = cache.Set(
+            tokenSourceKey,
+            new CancellationTokenSource(),
+            new MemoryCacheEntryOptions { Size = 1 });
+
+        return new CancellationChangeToken(source.Token);
+    }
+
+    /// <summary>
+    /// Invalidate a cached element's value
+    /// </summary>
+    /// <param name="cache">An <see cref="IMemoryCache"/> object</param>
+    /// <param name="key">The key of the cached element</param>
+    /// <returns>The element invalidated successfully or not</returns>
+    public static bool Invalidate(this IMemoryCache cache, string key)
+    {
+        var tokenSourceKey = key + Postfix;
+
+        if (!cache.TryGetValue(tokenSourceKey, out CancellationTokenSource source))
+            return false;
+
+        source.Cancel();
+        cache.Remove(tokenSourceKey);
+
+        return true;
+    }
+}