mcs/class/System.Threading.Tasks.Dataflow/System.Threading.Tasks.Dataflow/AsyncExecutingMessageBox.cs

   1 // AsyncExecutingMessageBox.cs
   2 //
   3 // Copyright (c) 2011 Jérémie "garuma" Laval
   4 // Copyright (c) 2012 Petr Onderka
   5 //
   6 // Permission is hereby granted, free of charge, to any person obtaining a copy
   7 // of this software and associated documentation files (the "Software"), to deal
   8 // in the Software without restriction, including without limitation the rights
   9 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10 // copies of the Software, and to permit persons to whom the Software is
  11 // furnished to do so, subject to the following conditions:
  12 //
  13 // The above copyright notice and this permission notice shall be included in
  14 // all copies or substantial portions of the Software.
  15 //
  16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22 // THE SOFTWARE.
  23
  24 using System.Collections.Concurrent;
  25
  26 namespace System.Threading.Tasks.Dataflow {
  27         class AsyncExecutingMessageBox<TInput, TTask>
  28                 : ExecutingMessageBoxBase<TInput>
  29                 where TTask : Task {
  30                 public delegate bool AsyncProcessItem (out TTask task);
  31
  32                 readonly AsyncProcessItem processItem;
  33                 readonly Action<TTask> processFinishedTask;
  34
  35                 public AsyncExecutingMessageBox (
  36                         ITargetBlock<TInput> target, BlockingCollection<TInput> messageQueue,
  37                         CompletionHelper compHelper, Func<bool> externalCompleteTester,
  38                         AsyncProcessItem processItem, Action<TTask> processFinishedTask,
  39                         Action outgoingQueueComplete, ExecutionDataflowBlockOptions options)
  40                         : base (
  41                                 target, messageQueue, compHelper, externalCompleteTester,
  42                                 outgoingQueueComplete, options)
  43                 {
  44                         this.processItem = processItem;
  45                         this.processFinishedTask = processFinishedTask;
  46                 }
  47
  48                 protected override void ProcessQueue ()
  49                 {
  50                         StartProcessQueue ();
  51
  52                         ProcessQueueWithoutStart ();
  53                 }
  54
  55                 void ProcessQueueWithoutStart ()
  56                 {
  57                         // catch is needed here, if the Task-returning delegate throws exception itself
  58                         try {
  59                                 int i = 0;
  60                                 while (CanRun (i)) {
  61                                         TTask task;
  62                                         if (!processItem (out task))
  63                                                 break;
  64                                         if (task == null || task.IsCanceled
  65                                             || (task.IsCompleted && !task.IsFaulted)) {
  66                                                 if (processFinishedTask != null)
  67                                                         processFinishedTask (task);
  68                                         } else if (task.IsFaulted) {
  69                                                 CompHelper.RequestFault (task.Exception, false);
  70                                                 break;
  71                                         } else {
  72                                                 task.ContinueWith (
  73                                                         t => TaskFinished ((TTask)t), Options.TaskScheduler);
  74                                                 return;
  75                                         }
  76                                         i++;
  77                                 }
  78                         } catch (Exception e) {
  79                                 CompHelper.RequestFault (e, false);
  80                         }
  81
  82                         FinishProcessQueue ();
  83                 }
  84
  85                 void TaskFinished (TTask task)
  86                 {
  87                         if (task.IsFaulted) {
  88                                 CompHelper.RequestFault (task.Exception, false);
  89                                 FinishProcessQueue ();
  90                                 return;
  91                         }
  92
  93                         if (processFinishedTask != null)
  94                                 processFinishedTask (task);
  95
  96                         ProcessQueueWithoutStart ();
  97                 }
  98         }
  99 }