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

   1 // ExecutingMessageBox.cs
   2 //
   3 // Copyright (c) 2011 Jérémie "garuma" Laval
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining a copy
   6 // of this software and associated documentation files (the "Software"), to deal
   7 // in the Software without restriction, including without limitation the rights
   8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 // copies of the Software, and to permit persons to whom the Software is
  10 // furnished to do so, subject to the following conditions:
  11 //
  12 // The above copyright notice and this permission notice shall be included in
  13 // all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 // THE SOFTWARE.
  22 //
  23 //
  24
  25
  26 using System;
  27 using System.Threading.Tasks;
  28 using System.Collections.Generic;
  29 using System.Collections.Concurrent;
  30
  31 namespace System.Threading.Tasks.Dataflow
  32 {
  33         internal class ExecutingMessageBox<TInput> : MessageBox<TInput>
  34         {
  35                 readonly ExecutionDataflowBlockOptions dataflowBlockOptions;
  36                 readonly BlockingCollection<TInput> messageQueue;
  37                 readonly Action processQueue;
  38                 readonly CompletionHelper compHelper;
  39
  40                 AtomicBoolean started = new AtomicBoolean ();
  41
  42                 public ExecutingMessageBox (BlockingCollection<TInput> messageQueue,
  43                                             CompletionHelper compHelper,
  44                                             Func<bool> externalCompleteTester,
  45                                             Action processQueue,
  46                                             ExecutionDataflowBlockOptions dataflowBlockOptions) : base (messageQueue, compHelper, externalCompleteTester)
  47                 {
  48                         this.messageQueue = messageQueue;
  49                         this.dataflowBlockOptions = dataflowBlockOptions;
  50                         this.processQueue = processQueue;
  51                         this.compHelper = compHelper;
  52                 }
  53
  54                 protected override void EnsureProcessing ()
  55                 {
  56                         if (!started.TryRelaxedSet ())
  57                                 return;
  58
  59                         Task[] tasks = new Task[dataflowBlockOptions.MaxDegreeOfParallelism];
  60                         for (int i = 0; i < tasks.Length; ++i)
  61                                 tasks[i] = Task.Factory.StartNew (processQueue);
  62                         Task.Factory.ContinueWhenAll (tasks, (_) => {
  63                                 started.Value = false;
  64                                 // Re-run ourselves in case of a race when data is available in the end
  65                                 if (messageQueue.Count > 0)
  66                                         EnsureProcessing ();
  67                                 else if (messageQueue.IsCompleted)
  68                                         compHelper.Complete ();
  69                         });
  70                 }
  71         }
  72 }
  73