#17868: Isolating background tasks

Work Items: 17868

--HG--
branch : 1.x

src/Orchard/Tasks/BackgroundService.cs

@@ -1,4 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Transactions;
 using JetBrains.Annotations;
+using Orchard.Data;
+using Orchard.Events;
 using Orchard.Logging;
 
 namespace Orchard.Tasks {
@@ -9,9 +15,9 @@ namespace Orchard.Tasks {
 
     [UsedImplicitly]
     public class BackgroundService : IBackgroundService {
-        private readonly IBackgroundTask _tasks;
+        private readonly IEnumerable<IEventHandler> _tasks;
 
-        public BackgroundService(IBackgroundTask tasks) {
+        public BackgroundService(IEnumerable<IEventHandler> tasks) {
             _tasks = tasks;
             Logger = NullLogger.Instance;
         }
@@ -19,7 +25,17 @@ namespace Orchard.Tasks {
         public ILogger Logger { get; set; }
 
         public void Sweep() {
-            _tasks.Sweep();
+            foreach(var task in _tasks.OfType<IBackgroundTask>()) {
+                using (var scope = new TransactionScope(TransactionScopeOption.RequiresNew)) {
+                    try {
+                        task.Sweep();
+                        scope.Complete();
+                    }
+                    catch (Exception e) {
+                        Logger.Error(e, "Error while processing background task");
+                    }
+                }
+            }
         }
     }
 }

src/Orchard/Tasks/SweepGenerator.cs

@@ -5,7 +5,7 @@ using Orchard.Environment;
 using Orchard.Logging;
 
 namespace Orchard.Tasks {
-    public class SweepGenerator : IOrchardShellEvents, IDisposable {
+    public class SweepGenerator : IOrchardShellEvents {
         private readonly IWorkContextAccessor _workContextAccessor;
         private readonly Timer _timer;
 
@@ -55,29 +55,11 @@ namespace Orchard.Tasks {
         }
 
         public void DoWork() {
-            // makes an inner container, similar to the per-request container
             using (var scope = _workContextAccessor.CreateWorkContextScope()) {
-                var transactionManager = scope.Resolve<ITransactionManager>();
-
-                try {
-                    // resolve the manager and invoke it
-                    var manager = scope.Resolve<IBackgroundService>();
-                    manager.Sweep();
-                }
-                catch {
-                    // any database changes in this using scope are invalidated
-                    transactionManager.Cancel();
-
-                    // pass exception along to actual handler
-                    throw;
-                }
+                // resolve the manager and invoke it
+                var manager = scope.Resolve<IBackgroundService>();
+                manager.Sweep();
             }
         }
-
-        public void Dispose()
-        {
-            _timer.Elapsed -= Elapsed;
-            _timer.Dispose();
-        }
     }
 }