only actors can save me

Management/Services/Files/FileStorageManagerCached.cs

@@ -0,0 +1,50 @@
+
+using System.Diagnostics.CodeAnalysis;
+using LocalModels;
+
+public class FileStorageManagerCached : IFileStorageManager
+{
+  private readonly FileStorageManager manager;
+
+  private readonly object cacheLock = new object();  // Lock object for synchronization
+
+
+  private DateTime? cacheTime { get; set; } = null;
+  private IEnumerable<LocalCourse>? cachedCourses { get; set; } = null;
+  private ILogger<FileStorageManagerCached> logger { get; }
+
+  private readonly int cacheSeconds = 2;
+  public FileStorageManagerCached(FileStorageManager manager, ILogger<FileStorageManagerCached> logger)
+  {
+    this.manager = manager;
+    this.logger = logger;
+  }
+  public IEnumerable<string> GetEmptyDirectories()
+  {
+    return manager.GetEmptyDirectories();
+  }
+
+  public async Task<IEnumerable<LocalCourse>> LoadSavedCourses()
+  {
+
+    var secondsFromLastLoad = (DateTime.Now - cacheTime)?.Seconds;
+
+    if (cachedCourses != null && secondsFromLastLoad < cacheSeconds)
+    {
+      logger.LogInformation("returning cached courses from file");
+      return cachedCourses;
+    }
+
+    cachedCourses = await manager.LoadSavedCourses();
+    cacheTime = DateTime.Now;
+    return cachedCourses;
+  }
+
+  public async Task SaveCourseAsync(LocalCourse course, LocalCourse? previouslyStoredCourse)
+  {
+    // race condition...
+    cacheTime = null;
+    cachedCourses = null;
+    await manager.SaveCourseAsync(course, previouslyStoredCourse);
+  }
+}