Refactored to task based jobs. Still not taking full advantage of tas…

…ks, but this sets the stage for that later.

README.md

@@ -32,4 +32,8 @@ tasks to run without requiring a bunch of setup or a connection to Azure.
 This is not a general purpose scheduling framework. There are much better ones 
 out there such as FluentScheduler and Quartz.net. The goal of this project is 
 to handle one task only, manage a recurring task on an interval in the 
-background for a web app.
+background for a web app.
+
+The needs I have are very simple. I didn't need a high fidelity scheduler. 
+Maybe later, I'll look to integrate what I've done with one of the others. 
+But for now, this scratches an itch.

src/WebBackgrounder.DemoWeb/SampleJob.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Threading;
+using System.Threading.Tasks;
 
 namespace WebBackgrounder.DemoWeb
 {
@@ -9,9 +10,9 @@ public SampleJob(TimeSpan interval) : base("Sample Job", interval)
         {
         }
 
-        public override void Execute()
+        public override Task Execute()
         {
-            Thread.Sleep(3000);
+            return new Task(() => Thread.Sleep(3000));
         }
     }
 }

src/WebBackgrounder.DemoWeb/WebBackgrounder.DemoWeb.csproj

@@ -146,7 +146,7 @@
         <WebProjectProperties>
           <UseIIS>False</UseIIS>
           <AutoAssignPort>True</AutoAssignPort>
-          <DevelopmentServerPort>56071</DevelopmentServerPort>
+          <DevelopmentServerPort>63168</DevelopmentServerPort>
           <DevelopmentServerVPath>/</DevelopmentServerVPath>
           <IISUrl>
           </IISUrl>

src/WebBackgrounder.EntityFramework/WorkItemCleanupJob.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using System.Threading.Tasks;
 using WebBackgrounder.EntityFramework.Entities;
 
 namespace WebBackgrounder.EntityFramework
@@ -28,24 +29,27 @@ public int MaxWorkItemCount
             private set;
         }
 
-        public override void Execute()
+        public override Task Execute()
         {
-            var count = _context.WorkItems.Count();
-            if (count > MaxWorkItemCount)
+            return new Task(() =>
             {
-                var oldest = (from workItem in _context.WorkItems
-                                orderby workItem.Started descending
-                                select workItem).Skip(MaxWorkItemCount).ToList();
-
-                if (oldest.Count > 0)
+                var count = _context.WorkItems.Count();
+                if (count > MaxWorkItemCount)
                 {
-                    foreach (var workItem in oldest)
+                    var oldest = (from workItem in _context.WorkItems
+                                    orderby workItem.Started descending
+                                    select workItem).Skip(MaxWorkItemCount).ToList();
+
+                    if (oldest.Count > 0)
                     {
-                        _context.WorkItems.Remove(workItem);
+                        foreach (var workItem in oldest)
+                        {
+                            _context.WorkItems.Remove(workItem);
+                        }
+                        _context.SaveChanges();
                     }
-                    _context.SaveChanges();
                 }
-            }
+            });
         }
     }
 }

src/WebBackgrounder.UnitTests/JobHostFacts.cs

@@ -13,25 +13,32 @@ public class TheStopMethod
             public void EnsuresNoWorkIsDone()
             {
                 var host = new JobHost();
-                Action work = () => { throw new InvalidOperationException("Hey, this is supposed to be shut down!"); };
+                var task = new Task(() => { throw new InvalidOperationException("Hey, this is supposed to be shut down!"); });
 
                 host.Stop(true);
 
-                host.DoWork(work);
+                host.DoWork(task);
             }
 
             [Fact]
             public void WaitsForTaskToComplete()
             {
                 var host = new JobHost();
-                var workTask = new Task(() => host.DoWork(() => Thread.Sleep(100)));
+                var workTask = new Task(() => host.DoWork(new Task(() =>
+                {
+                    // Was getting inconsistent results with Thread.Sleep(100)
+                    for (int i = 0; i < 100; i++)
+                    {
+                        Thread.Sleep(1);
+                    }
+                })));
                 var beforeStop = DateTime.UtcNow;
                 workTask.Start();
                 while (workTask.Status != TaskStatus.Running)
                 {
                     Thread.Sleep(1);
                 }
-
+                
                 host.Stop(false);
                 var afterStop = DateTime.UtcNow;
 

src/WebBackgrounder.UnitTests/ScheduleFacts.cs

@@ -41,9 +41,11 @@ public void ReturnsTheSpanBetweenNowAndNextRunTime()
             [Fact]
             public void ReturnsTheSpanBetweenNowAndNextRunTimeFiguringInLastRun()
             {
+                var now = DateTime.UtcNow;
+
                 var job = new Mock<IJob>();
                 job.Setup(j => j.Interval).Returns(TimeSpan.FromSeconds(30));
-                var schedule = new Schedule(job.Object) { LastRunTime = DateTime.UtcNow.AddSeconds(-20)};
+                var schedule = new Schedule(job.Object, () => now) { LastRunTime = now.AddSeconds(-20)};
 
                 var interval = schedule.GetIntervalToNextRun();
 

src/WebBackgrounder.UnitTests/SchedulerFacts.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
 using Moq;
 using Xunit;
 
@@ -103,8 +105,9 @@ public WaitJob(int intervalSeconds) : base("Waits", TimeSpan.FromSeconds(interva
 
                 public int Id { get; private set; }
 
-                public override void Execute()
+                public override Task Execute()
                 {
+                    return new Task(() => Thread.Sleep(1));
                 }
             }
         }

src/WebBackgrounder.UnitTests/WorkItemCleanupJobFacts.cs

@@ -24,8 +24,9 @@ public void DeletesItemsBeyondMaxCount()
                     new WorkItem {Id = 104, Started = DateTime.UtcNow}, 
                 };
                 var job = new WorkItemCleanupJob(2, TimeSpan.FromSeconds(1), context.Object);
-
-                job.Execute();
+                var task = job.Execute();
+                task.Start();
+                task.Wait();
 
                 Assert.Equal(2, context.Object.WorkItems.Count());
                 Assert.Equal(101, context.Object.WorkItems.First().Id);

src/WebBackgrounder/IJob.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 namespace WebBackgrounder
 {
@@ -9,11 +10,7 @@ public interface IJob
         /// </summary>
         string Name { get; }
 
-        /// <summary>
-        /// Executes the task
-        /// </summary>
-        /// <returns></returns>
-        void Execute();
+        Task Execute();
 
         /// <summary>
         /// Interval in milliseconds.

src/WebBackgrounder/IJobCoordinator.cs

@@ -1,11 +1,13 @@
-namespace WebBackgrounder
+using System.Threading.Tasks;
+
+namespace WebBackgrounder
 {
     public interface IJobCoordinator
     {
         /// <summary>
-        /// Coordinates the work to be done and then does the work if necessary.
+        /// Coordinates the work to be done and returns a task embodying that work.
         /// </summary>
         /// <param name="job"></param>
-        void PerformWork(IJob job);
+        Task PerformWork(IJob job);
     }
 }

src/WebBackgrounder/IJobHost.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 namespace WebBackgrounder
 {
@@ -8,6 +9,6 @@ namespace WebBackgrounder
     /// </summary>
     public interface IJobHost
     {
-        void DoWork(Action work);
+        void DoWork(Task work);
     }
 }

src/WebBackgrounder/Job.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 namespace WebBackgrounder
 {
@@ -22,7 +23,7 @@ public string Name
             private set;
         }
 
-        public abstract void Execute();
+        public abstract Task Execute();
 
         public TimeSpan Interval 
         { 

src/WebBackgrounder/JobHost.cs

@@ -1,12 +1,12 @@
-using System;
+using System.Threading.Tasks;
 using System.Web.Hosting;
 
 namespace WebBackgrounder
 {
     public class JobHost : IJobHost, IRegisteredObject
     {
-        private readonly object _lock = new object();
-        private bool _shuttingDown;
+        readonly object _lock = new object();
+        bool _shuttingDown;
 
         public JobHost()
         {
@@ -19,17 +19,24 @@ public void Stop(bool immediate)
             {
                 _shuttingDown = true;
             }
+            HostingEnvironment.UnregisterObject(this);
         }
 
-        public void DoWork(Action work)
+        public void DoWork(Task work)
         {
             lock (_lock)
             {
                 if (_shuttingDown)
                 {
                     return;
                 }
-                work();
+                work.Start();
+                // Need to hold the lock until the task completes.
+                // Later on, we should take advantage of the fact that the work is represented 
+                // by a task. Instead of locking, we could simply have the Stop method cancel 
+                // any pending tasks.
+                work.Wait();
+
             }
         }
     }

src/WebBackgrounder/JobManager.cs

@@ -71,7 +71,7 @@ void PerformTask()
         {
             using (var schedule = _scheduler.Next())
             {
-                _host.DoWork(() => _coordinator.PerformWork(schedule.Job));
+                _host.DoWork(_coordinator.PerformWork(schedule.Job));
             }
         }
 

src/WebBackgrounder/SingleServerJobCoordinator.cs

@@ -1,10 +1,12 @@
- namespace WebBackgrounder
+ using System.Threading.Tasks;
+
+namespace WebBackgrounder
 {
     public class SingleServerJobCoordinator : IJobCoordinator
     {
-        public void PerformWork(IJob job)
+        public Task PerformWork(IJob job)
         {
-            job.Execute();
+            return job.Execute();
         }
     }
 }

src/WebBackgrounder/WebFarmJobCoordinator.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 namespace WebBackgrounder
 {
@@ -15,32 +16,37 @@ public WebFarmJobCoordinator(Func<string, IWorkItemRepository> repositoryThunk)
             _repositoryThunk = repositoryThunk;
         }
 
-        public void PerformWork(IJob jobWorker)
+        public Task PerformWork(IJob job)
         {
             // We need a new instance every time we perform work.
-            var repository = _repositoryThunk(jobWorker.Name);
+            var repository = _repositoryThunk(job.Name);
 
             var unitOfWork = ReserveWork(repository, WorkerId);
             if (unitOfWork == null)
             {
-                return;
+                return null;
             }
 
-            try
-            {
-                jobWorker.Execute();
-                unitOfWork.Complete();
-            }
-            catch (Exception exception)
+            var task = job.Execute();
+            task.ContinueWith(c =>
             {
-                unitOfWork.Fail(exception);
-            }
+                if (c.IsFaulted)
+                {
+                    unitOfWork.Fail(c.Exception.GetBaseException());
+                }
+                else
+                {
+                    unitOfWork.Complete();
+                }
+
+            });
+            return task;
         }
 
         public JobUnitOfWork ReserveWork(IWorkItemRepository repository, string workerId)
         {
             long? workItemId = null;
-            
+
             // We do a double check here because this is the first query we run and 
             // a database can't be created inside a transaction scope.
             if (repository.AnyActiveWorker)

src/WebBackgrounderSolution.sln

@@ -9,6 +9,11 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WebBackgrounder.UnitTests",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WebBackgrounder.EntityFramework", "WebBackgrounder.EntityFramework\WebBackgrounder.EntityFramework.csproj", "{06D8DE5D-F101-4CD5-B406-8A211216FCE1}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Meta", "Meta", "{3F870BEB-5F40-4CC3-9226-2FBE7A930E81}"
+	ProjectSection(SolutionItems) = preProject
+		..\README.md = ..\README.md
+	EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU