latest entity caching primitives

1 files changed, 70 insertions, 0 deletions

diff --git a/lib/VNLib.Plugins.Extensions.VNCache/src/DataModel/WriteBackCachePolicy.cs b/lib/VNLib.Plugins.Extensions.VNCache/src/DataModel/WriteBackCachePolicy.cs
new file mode 100644
index 0000000..93434de
--- /dev/null
+++ b/lib/VNLib.Plugins.Extensions.VNCache/src/DataModel/WriteBackCachePolicy.cs
@@ -0,0 +1,70 @@
+/*
+* Copyright (c) 2024 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Extensions.VNCache
+* File: WriteBackCachePolicy.cs 
+*
+* WriteBackCachePolicy.cs is part of VNLib.Plugins.Extensions.VNCache 
+* which is part of the larger VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Extensions.VNCache is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Plugins.Extensions.VNCache is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System;
+using System.Threading.Tasks;
+using System.Diagnostics;
+
+namespace VNLib.Plugins.Extensions.VNCache.DataModel
+{
+    /// <summary>
+    /// Provides a policy for observing the completion of cache operations
+    /// </summary>
+    /// <param name="onFaulted">
+    /// A callback function that is executed when a cache operation has fauled due to an exception
+    /// </param>
+    public class WriteBackCachePolicy(Action<Task> onFaulted) : ICacheTaskPolicy
+    {
+        ///<inheritdoc/>
+        public Task ObserveOperationAsync(Task operation)
+        {
+            ArgumentNullException.ThrowIfNull(operation);
+
+            if (!operation.IsCompleted)
+            {
+                //Defer the observation to the callback function to watch for errors
+                _ = operation.ContinueWith(
+                    ObserveOperation, 
+                    cancellationToken: default,
+                    TaskContinuationOptions.ExecuteSynchronously,
+                    TaskScheduler.Default
+                );
+            }
+
+            return Task.CompletedTask;
+        }
+
+        private void ObserveOperation(Task operation)
+        {
+            //Should only be called on a completed task
+            Debug.Assert(operation.IsCompleted);
+
+            if (operation.IsFaulted)
+            {
+                onFaulted(operation);
+            }
+        }
+    }
+   
+}