more granular Concurrency control.

indexer calls are done fully paralleled.
events are dispatched on max of 2 threads.

NzbDrone.Common.Test/EventingTests/MessageAggregatorEventTests.cs

@@ -1,9 +1,11 @@
 using System;
 using System.Collections.Generic;
+using System.Threading;
 using Moq;
 using NUnit.Framework;
 using NzbDrone.Common.Messaging;
 using NzbDrone.Test.Common;
+using FluentAssertions;
 
 namespace NzbDrone.Common.Test.EventingTests
 {
@@ -16,6 +18,8 @@ namespace NzbDrone.Common.Test.EventingTests
         private Mock<IHandle<EventB>> HandlerB1;
         private Mock<IHandle<EventB>> HandlerB2;
 
+        private Mock<IHandleAsync<EventA>> AsyncHandlerA1;
+
 
         [SetUp]
         public void Setup()
@@ -25,6 +29,8 @@ namespace NzbDrone.Common.Test.EventingTests
             HandlerB1 = new Mock<IHandle<EventB>>();
             HandlerB2 = new Mock<IHandle<EventB>>();
 
+            AsyncHandlerA1 = new Mock<IHandleAsync<EventA>>();
+
             Mocker.GetMock<IServiceFactory>()
                   .Setup(c => c.BuildAll<IHandle<EventA>>())
                   .Returns(new List<IHandle<EventA>> { HandlerA1.Object, HandlerA2.Object });
@@ -79,6 +85,50 @@ namespace NzbDrone.Common.Test.EventingTests
             ExceptionVerification.ExpectedErrors(1);
         }
 
+
+        [Test]
+        public void should_queue_multiple_async_events()
+        {
+            var eventA = new EventA();
+
+
+
+            var handlers = new List<IHandleAsync<EventA>>
+                {
+                    AsyncHandlerA1.Object, 
+                    AsyncHandlerA1.Object,
+                    AsyncHandlerA1.Object,
+                    AsyncHandlerA1.Object,
+                    AsyncHandlerA1.Object,
+                    AsyncHandlerA1.Object, 
+                    AsyncHandlerA1.Object,
+                };
+
+            Mocker.GetMock<IServiceFactory>()
+          .Setup(c => c.BuildAll<IHandle<EventA>>())
+          .Returns(new List<IHandle<EventA>>());
+
+            Mocker.GetMock<IServiceFactory>()
+                  .Setup(c => c.BuildAll<IHandleAsync<EventA>>())
+                  .Returns(handlers);
+
+            var counter = new ConcurrencyCounter(handlers.Count);
+
+
+            AsyncHandlerA1.Setup(c => c.HandleAsync(It.IsAny<EventA>()))
+                .Callback<EventA>(c =>
+                    {
+                        var id = counter.Start();
+                        Thread.Sleep(1000);
+                        counter.Stop(id);
+                    });
+
+            Subject.PublishEvent(eventA);
+
+            counter.WaitForAllItems();
+
+            counter.MaxThreads.Should().Be(2);
+        }
     }
 
 

NzbDrone.Common/Messaging/LimitedConcurrencyLevelTaskScheduler.cs

@@ -0,0 +1,133 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace NzbDrone.Common.Messaging
+{
+    public class LimitedConcurrencyLevelTaskScheduler : TaskScheduler
+    {
+        /// <summary>Whether the current thread is processing work items.</summary>
+        [ThreadStatic]
+        private static bool _currentThreadIsProcessingItems;
+        /// <summary>The list of tasks to be executed.</summary> 
+        private readonly LinkedList<Task> _tasks = new LinkedList<Task>(); // protected by lock(_tasks) 
+        /// <summary>The maximum concurrency level allowed by this scheduler.</summary> 
+        private readonly int _maxDegreeOfParallelism;
+        /// <summary>Whether the scheduler is currently processing work items.</summary> 
+        private int _delegatesQueuedOrRunning = 0; // protected by lock(_tasks) 
+
+        /// <summary> 
+        /// Initializes an instance of the LimitedConcurrencyLevelTaskScheduler class with the 
+        /// specified degree of parallelism. 
+        /// </summary> 
+        /// <param name="maxDegreeOfParallelism">The maximum degree of parallelism provided by this scheduler.</param>
+        public LimitedConcurrencyLevelTaskScheduler(int maxDegreeOfParallelism)
+        {
+            if (maxDegreeOfParallelism < 1) throw new ArgumentOutOfRangeException("maxDegreeOfParallelism");
+            _maxDegreeOfParallelism = maxDegreeOfParallelism;
+        }
+
+        /// <summary>Queues a task to the scheduler.</summary> 
+        /// <param name="task">The task to be queued.</param>
+        protected sealed override void QueueTask(Task task)
+        {
+            // Add the task to the list of tasks to be processed.  If there aren't enough 
+            // delegates currently queued or running to process tasks, schedule another. 
+            lock (_tasks)
+            {
+                _tasks.AddLast(task);
+                if (_delegatesQueuedOrRunning < _maxDegreeOfParallelism)
+                {
+                    ++_delegatesQueuedOrRunning;
+                    NotifyThreadPoolOfPendingWork();
+                }
+            }
+        }
+
+        /// <summary> 
+        /// Informs the ThreadPool that there's work to be executed for this scheduler. 
+        /// </summary> 
+        private void NotifyThreadPoolOfPendingWork()
+        {
+            ThreadPool.UnsafeQueueUserWorkItem(_ =>
+                {
+                    // Note that the current thread is now processing work items. 
+                    // This is necessary to enable inlining of tasks into this thread.
+                    _currentThreadIsProcessingItems = true;
+                    try
+                    {
+                        // Process all available items in the queue. 
+                        while (true)
+                        {
+                            Task item;
+                            lock (_tasks)
+                            {
+                                // When there are no more items to be processed, 
+                                // note that we're done processing, and get out. 
+                                if (_tasks.Count == 0)
+                                {
+                                    --_delegatesQueuedOrRunning;
+                                    break;
+                                }
+
+                                // Get the next item from the queue
+                                item = _tasks.First.Value;
+                                _tasks.RemoveFirst();
+                            }
+
+                            // Execute the task we pulled out of the queue 
+                            base.TryExecuteTask(item);
+                        }
+                    }
+                    // We're done processing items on the current thread 
+                    finally { _currentThreadIsProcessingItems = false; }
+                }, null);
+        }
+
+        /// <summary>Attempts to execute the specified task on the current thread.</summary> 
+        /// <param name="task">The task to be executed.</param>
+        /// <param name="taskWasPreviouslyQueued"></param>
+        /// <returns>Whether the task could be executed on the current thread.</returns> 
+        protected sealed override bool TryExecuteTaskInline(Task task, bool taskWasPreviouslyQueued)
+        {
+            // If this thread isn't already processing a task, we don't support inlining 
+            if (!_currentThreadIsProcessingItems) return false;
+
+            // If the task was previously queued, remove it from the queue 
+            if (taskWasPreviouslyQueued) TryDequeue(task);
+
+            // Try to run the task. 
+            return base.TryExecuteTask(task);
+        }
+
+        /// <summary>Attempts to remove a previously scheduled task from the scheduler.</summary> 
+        /// <param name="task">The task to be removed.</param>
+        /// <returns>Whether the task could be found and removed.</returns> 
+        protected sealed override bool TryDequeue(Task task)
+        {
+            lock (_tasks) return _tasks.Remove(task);
+        }
+
+        /// <summary>Gets the maximum concurrency level supported by this scheduler.</summary> 
+        public sealed override int MaximumConcurrencyLevel { get { return _maxDegreeOfParallelism; } }
+
+        /// <summary>Gets an enumerable of the tasks currently scheduled on this scheduler.</summary> 
+        /// <returns>An enumerable of the tasks currently scheduled.</returns> 
+        protected sealed override IEnumerable<Task> GetScheduledTasks()
+        {
+            bool lockTaken = false;
+            try
+            {
+                Monitor.TryEnter(_tasks, ref lockTaken);
+                if (lockTaken) return _tasks.ToArray();
+                else throw new NotSupportedException();
+            }
+            finally
+            {
+                if (lockTaken) Monitor.Exit(_tasks);
+            }
+        }
+    }
+}

NzbDrone.Common/Messaging/MessageAggregator.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Linq;
-using System.Reflection;
 using System.Threading.Tasks;
 using NLog;
 using NzbDrone.Common.EnsureThat;
@@ -12,11 +11,14 @@ namespace NzbDrone.Common.Messaging
     {
         private readonly Logger _logger;
         private readonly IServiceFactory _serviceFactory;
+        private readonly TaskFactory _taskFactory;
 
         public MessageAggregator(Logger logger, IServiceFactory serviceFactory)
         {
             _logger = logger;
             _serviceFactory = serviceFactory;
+            var scheduler = new LimitedConcurrencyLevelTaskScheduler(2);
+            _taskFactory = new TaskFactory(scheduler);
         }
 
         public void PublishEvent<TEvent>(TEvent @event) where TEvent : class ,IEvent
@@ -45,12 +47,13 @@ namespace NzbDrone.Common.Messaging
             foreach (var handler in _serviceFactory.BuildAll<IHandleAsync<TEvent>>())
             {
                 var handlerLocal = handler;
-                Task.Factory.StartNew(() =>
+
+                _taskFactory.StartNew(() =>
                 {
                     _logger.Debug("{0} ~> {1}", eventName, handlerLocal.GetType().Name);
                     handlerLocal.HandleAsync(@event);
                     _logger.Debug("{0} <~ {1}", eventName, handlerLocal.GetType().Name);
-                });
+                }, TaskCreationOptions.PreferFairness);
             }
         }
 

NzbDrone.Common/NzbDrone.Common.csproj

@@ -102,6 +102,7 @@
     <Compile Include="EnsureThat\ExpressionExtensions.cs" />
     <Compile Include="EnsureThat\Param.cs" />
     <Compile Include="EnsureThat\Resources\ExceptionMessages.Designer.cs" />
+    <Compile Include="Messaging\LimitedConcurrencyLevelTaskScheduler.cs" />
     <Compile Include="StringExtensions.cs" />
     <Compile Include="EnsureThat\TypeParam.cs" />
     <Compile Include="HashUtil.cs" />

NzbDrone.Core.Test/IndexerSearchTests/FetchAndParseRssServiceFixture.cs

@@ -0,0 +1,78 @@
+using System.Collections.Generic;
+using FizzWare.NBuilder;
+using FluentAssertions;
+using Moq;
+using NUnit.Framework;
+using NzbDrone.Core.DecisionEngine;
+using NzbDrone.Core.IndexerSearch;
+using NzbDrone.Core.IndexerSearch.Definitions;
+using NzbDrone.Core.Indexers;
+using NzbDrone.Core.Indexers.Newznab;
+using NzbDrone.Core.Parser.Model;
+using NzbDrone.Core.Test.Framework;
+using NzbDrone.Core.Tv;
+using NzbDrone.Test.Common;
+
+namespace NzbDrone.Core.Test.IndexerSearchTests
+{
+    public class NzbSearchServiceFixture : CoreTest<NzbSearchService>
+    {
+        private List<IIndexer> _indexers;
+
+        private Series _searchTargetSeries;
+
+        [SetUp]
+        public void Setup()
+        {
+
+            _searchTargetSeries = Builder<Series>.CreateNew().BuildNew();
+
+            _indexers = new List<IIndexer>();
+
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+            _indexers.Add(new Newznab());
+
+            Mocker.SetConstant<IEnumerable<IIndexer>>(_indexers);
+
+            Mocker.GetMock<ISeriesService>().Setup(c => c.GetSeries(It.IsAny<int>()))
+                  .Returns(_searchTargetSeries);
+
+        }
+
+        [Test]
+        public void should_call_fetch_on_all_indexers_at_the_same_time()
+        {
+
+            var counter = new ConcurrencyCounter(_indexers.Count);
+
+            Mocker.GetMock<IFetchFeedFromIndexers>().Setup(c => c.Fetch(It.IsAny<IIndexer>(), It.IsAny<SingleEpisodeSearchDefinition>()))
+                  .Returns(new List<ReportInfo>())
+                  .Callback((() => counter.SimulateWork(500)));
+
+            Mocker.GetMock<IIndexerService>().Setup(c => c.GetAvailableIndexers()).Returns(_indexers);
+
+            Mocker.GetMock<IMakeDownloadDecision>()
+                  .Setup(c => c.GetSearchDecision(It.IsAny<IEnumerable<ReportInfo>>(), It.IsAny<SearchDefinitionBase>()))
+                  .Returns(new List<DownloadDecision>());
+
+            Subject.SearchSingle(0, 0, 0);
+
+            counter.WaitForAllItems();
+
+            counter.MaxThreads.Should().Be(_indexers.Count);
+        }
+    }
+}

NzbDrone.Core.Test/IndexerTests/FetchAndParseRssServiceFixture.cs

@@ -9,6 +9,7 @@ using NzbDrone.Core.Indexers;
 using NzbDrone.Core.Indexers.Newznab;
 using NzbDrone.Core.Parser.Model;
 using NzbDrone.Core.Test.Framework;
+using NzbDrone.Test.Common;
 
 namespace NzbDrone.Core.Test.IndexerTests
 {
@@ -45,26 +46,20 @@ namespace NzbDrone.Core.Test.IndexerTests
         [Explicit]
         public void should_call_fetch_on_all_indexers_at_the_same_time()
         {
-            var callsToFetch = new List<DateTime>();
+
+            var counter = new ConcurrencyCounter(_indexers.Count);
 
             Mocker.GetMock<IFetchFeedFromIndexers>().Setup(c => c.FetchRss(It.IsAny<IIndexer>()))
                 .Returns(new List<ReportInfo>())
-                  .Callback((() =>
-                      {
-                          Thread.Sleep(2000);
-                          Console.WriteLine(DateTime.Now);
-                          callsToFetch.Add(DateTime.Now);
-                      }));
+                  .Callback((() => counter.SimulateWork(500)));
 
             Mocker.GetMock<IIndexerService>().Setup(c => c.GetAvailableIndexers()).Returns(_indexers);
 
             Subject.Fetch();
 
+            counter.WaitForAllItems();
 
-            var first = callsToFetch.Min();
-            var last = callsToFetch.Max();
-
-            (last - first).Should().BeLessThan(TimeSpan.FromSeconds(1));
+            counter.MaxThreads.Should().Be(_indexers.Count);
         }
     }
 }

NzbDrone.Core.Test/NzbDrone.Core.Test.csproj

@@ -133,6 +133,7 @@
     <Compile Include="Framework\CoreTest.cs" />
     <Compile Include="Framework\DbTest.cs" />
     <Compile Include="Framework\NBuilderExtensions.cs" />
+    <Compile Include="IndexerSearchTests\FetchAndParseRssServiceFixture.cs" />
     <Compile Include="IndexerSearchTests\SearchDefinitionFixture.cs" />
     <Compile Include="IndexerTests\BasicRssParserFixture.cs" />
     <Compile Include="IndexerTests\FetchAndParseRssServiceFixture.cs" />

NzbDrone.Core/IndexerSearch/NzbSearchService.cs

@@ -112,21 +112,33 @@ namespace NzbDrone.Core.IndexerSearch
             var indexers = _indexerService.GetAvailableIndexers().ToList();
             var reports = new List<ReportInfo>();
 
-            Parallel.ForEach(indexers, indexer =>
+
+            var taskList = new List<Task>();
+            var taskFactory = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);
+
+            foreach (var indexer in indexers)
             {
-                try
+                var indexerLocal = indexer;
+
+                taskList.Add(taskFactory.StartNew(() =>
                 {
-                    var indexerReports = searchAction(indexer);
-                    lock (indexer)
+                    try
                     {
-                        reports.AddRange(indexerReports);
+                        var indexerReports = searchAction(indexerLocal);
+
+                        lock (reports)
+                        {
+                            reports.AddRange(indexerReports);
+                        }
                     }
-                }
-                catch (Exception e)
-                {
-                    _logger.ErrorException(String.Format("An error has occurred while searching for {0} from: {1}", definitionBase, indexer.Name), e);
-                }
-            });
+                    catch (Exception e)
+                    {
+                        _logger.ErrorException("Error while searching for " + definitionBase, e);
+                    }
+                }));
+            }
+
+            Task.WaitAll(taskList.ToArray());
 
             _logger.Debug("Total of {0} reports were found for {1} in {2} indexers", reports.Count, definitionBase, indexers.Count);
 

NzbDrone.Core/Indexers/FetchAndParseRssService.cs

@@ -38,15 +38,28 @@ namespace NzbDrone.Core.Indexers
 
             _logger.Debug("Available indexers {0}", indexers.Count);
 
-            Parallel.ForEach(indexers, new ParallelOptions { MaxDegreeOfParallelism = 10 }, indexer =>
-                {
-                    var indexerFeed = _feedFetcher.FetchRss(indexer);
-
-                    lock (result)
-                    {
-                        result.AddRange(indexerFeed);
-                    }
-                });
+
+            var taskList = new List<Task>();
+            var taskFactory = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);
+
+            foreach (var indexer in indexers)
+            {
+                var indexerLocal = indexer;
+
+                var task = taskFactory.StartNew(() =>
+                     {
+                         var indexerFeed = _feedFetcher.FetchRss(indexerLocal);
+
+                         lock (result)
+                         {
+                             result.AddRange(indexerFeed);
+                         }
+                     });
+
+                taskList.Add(task);
+            }
+
+            Task.WaitAll(taskList.ToArray());
 
             _logger.Debug("Found {0} reports", result.Count);
 

NzbDrone.Core/Tv/SeriesService.cs

@@ -2,20 +2,16 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using Marr.Data;
 using NLog;
 using NzbDrone.Common;
 using NzbDrone.Common.EnsureThat;
 using NzbDrone.Common.Messaging;
 using NzbDrone.Core.Configuration;
 using NzbDrone.Core.DataAugmentation.Scene;
-using NzbDrone.Core.Datastore;
 using NzbDrone.Core.MetadataSource;
 using NzbDrone.Core.Model;
 using NzbDrone.Core.Organizer;
-using NzbDrone.Core.Parser;
 using NzbDrone.Core.RootFolders;
-using NzbDrone.Core.SeriesStats;
 using NzbDrone.Core.Tv.Events;
 
 namespace NzbDrone.Core.Tv

NzbDrone.Test.Common/ConcurrencyCounter.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace NzbDrone.Test.Common
+{
+    public class ConcurrencyCounter
+    {
+        private int _items;
+        readonly object _mutex = new object();
+        readonly Dictionary<int, int> _threads = new Dictionary<int, int>();
+
+        public int MaxThreads { get { return _threads.Count; } }
+
+        public ConcurrencyCounter(int items)
+        {
+            _items = items;
+        }
+
+        public void WaitForAllItems()
+        {
+            while (_items != 0)
+            {
+                Thread.Sleep(500);
+            }
+        }
+
+        public int Start()
+        {
+            int threadId = Thread.CurrentThread.ManagedThreadId;
+            lock (_mutex)
+            {
+
+                _threads[threadId] = 1;
+            }
+
+            Console.WriteLine("Starting " + threadId);
+            return threadId;
+        }
+
+        public void SimulateWork(int sleepInMs)
+        {
+            var id = Start();
+            Thread.Sleep(sleepInMs);
+            Stop(id);
+        }
+
+        public void Stop(int id)
+        {
+            Console.WriteLine("Finished " + id);
+            lock (_mutex)
+            {
+                _items--;
+            }
+        }
+    }
+}

NzbDrone.Test.Common/NzbDrone.Test.Common.csproj

@@ -90,6 +90,7 @@
     <Compile Include="AutoMoq\AutoMoqer.cs" />
     <Compile Include="AutoMoq\Unity\AutoMockingBuilderStrategy.cs" />
     <Compile Include="AutoMoq\Unity\AutoMockingContainerExtension.cs" />
+    <Compile Include="ConcurrencyCounter.cs" />
     <Compile Include="ExceptionVerification.cs" />
     <Compile Include="Categories\IntegrationTestAttribute.cs" />
     <Compile Include="LoggingTest.cs" />