U4-9322 - filesystems & cleanup

src/Umbraco.Core/IO/ShadowFileSystems.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+using Umbraco.Core.Logging;
+
+namespace Umbraco.Core.IO
+{
+    internal class ShadowFileSystems : ICompletable
+    {
+        // note: taking a reference to the _manager instead of using manager.Current
+        // to avoid using Current everywhere but really, we support only 1 scope at
+        // a time, not multiple scopes in case of multiple managers (not supported)
+
+        private static readonly object Locker = new object();
+        private static Guid _currentId = Guid.Empty;
+        private readonly Guid _id;
+        private readonly ShadowWrapper[] _wrappers;
+        private bool _completed;
+
+        public ShadowFileSystems(Guid id, ShadowWrapper[] wrappers)
+        {
+            lock (Locker)
+            {
+                if (_currentId != Guid.Empty)
+                    throw new InvalidOperationException("Already shadowing.");
+                _currentId = id;
+
+                LogHelper.Debug<ShadowFileSystems>("Shadow " + id + ".");
+                _id = id;
+                _wrappers = wrappers;
+                foreach (var wrapper in _wrappers)
+                    wrapper.Shadow(id);
+            }
+        }
+
+        public void Complete()
+        {
+            _completed = true;
+        }
+
+        public void Dispose()
+        {
+            lock (Locker)
+            {
+                LogHelper.Debug<ShadowFileSystems>("UnShadow " + _id + " (" + (_completed ? "complete" : "abort") + ").");
+
+                var exceptions = new List<Exception>();
+                foreach (var wrapper in _wrappers)
+                {
+                    try
+                    {
+                        // this may throw an AggregateException if some of the changes could not be applied
+                        wrapper.UnShadow(_completed);
+                    }
+                    catch (AggregateException ae)
+                    {
+                        exceptions.Add(ae);
+                    }
+                }
+
+                _currentId = Guid.Empty;
+
+                if (exceptions.Count > 0)
+                    throw new AggregateException(_completed ? "Failed to apply all changes (see exceptions)." : "Failed to abort (see exceptions).", exceptions);
+            }
+        }
+
+        // for tests
+        internal static void ResetId()
+        {
+            _currentId = Guid.Empty;
+        }
+    }
+}