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source: trunk/sources/HeuristicLab.Clients.Hive/3.3/ConcurrentTaskDownloader.cs @ 7125

Last change on this file since 7125 was 7125, checked in by ascheibe, 12 years ago

#1672

  • removed magic numbers for upload retries
  • speed up job downloading by placing deserializing/downloading semaphores correctly
  • increased max. number of parallel downloads/deserializations
  • added more status messages when downloading to make it more clear what's actually happening
  • renamed some variables
File size: 5.3 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2011 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 */
20#endregion
21
22using System;
23using System.Threading;
24using System.Threading.Tasks;
25using HeuristicLab.Common;
26using HeuristicLab.Hive;
27
28namespace HeuristicLab.Clients.Hive {
29  /// <summary>
30  /// Downloads and deserializes jobs. It avoids too many jobs beeing downloaded or deserialized at the same time to avoid memory problems
31  /// </summary>
32  public class ConcurrentTaskDownloader<T> where T : class, ITask {
33    private bool abort = false;
34    // use semaphore to ensure only few concurrenct connections and few SerializedJob objects in memory
35    private Semaphore downloadSemaphore;
36    private Semaphore deserializeSemaphore;
37
38    public ConcurrentTaskDownloader(int concurrentDownloads, int concurrentDeserializations) {
39      downloadSemaphore = new Semaphore(concurrentDownloads, concurrentDownloads);
40      deserializeSemaphore = new Semaphore(concurrentDeserializations, concurrentDeserializations);
41      TaskScheduler.UnobservedTaskException += new EventHandler<UnobservedTaskExceptionEventArgs>(TaskScheduler_UnobservedTaskException);
42    }
43
44    public void DownloadTaskData(Task t, Action<Task, T> onFinishedAction) {
45      Task<Tuple<Task, T>> task = Task<Tuple<Task, TaskData>>.Factory.StartNew(DownloadTaskData, t)
46                                     .ContinueWith((y) => DeserializeTask(y.Result));
47
48      task.ContinueWith((x) => OnTaskFinished(x, onFinishedAction), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnRanToCompletion);
49      task.ContinueWith((x) => OnTaskFailed(x, onFinishedAction), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnFaulted);
50    }
51
52    public void DownloadTaskDataAndTask(Guid taskId, Action<Task, T> onFinishedAction) {
53      Task<Tuple<Task, T>> task = Task<Task>.Factory.StartNew(DownloadTask, taskId)
54                                     .ContinueWith((x) => DownloadTaskData(x.Result))
55                                     .ContinueWith((y) => DeserializeTask(y.Result));
56
57      task.ContinueWith((x) => OnTaskFinished(x, onFinishedAction), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnRanToCompletion);
58      task.ContinueWith((x) => OnTaskFailed(x, onFinishedAction), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnFaulted);
59    }
60
61    private void OnTaskFinished(Task<Tuple<Task, T>> task, Action<Task, T> onFinishedAction) {
62      onFinishedAction(task.Result.Item1, task.Result.Item2);
63    }
64    private void OnTaskFailed(Task<Tuple<Task, T>> task, Action<Task, T> onFinishedAction) {
65      task.Exception.Flatten().Handle((e) => { return true; });
66      OnExceptionOccured(task.Exception.Flatten());
67      onFinishedAction(task.Result.Item1, null);
68    }
69
70    private Task DownloadTask(object taskId) {
71      return ServiceLocator.Instance.CallHiveService(s => s.GetTask((Guid)taskId));
72    }
73
74    protected Tuple<Task, TaskData> DownloadTaskData(object taskId) {
75      return DownloadTaskData((Task)taskId);
76    }
77
78    protected Tuple<Task, TaskData> DownloadTaskData(Task task) {
79      downloadSemaphore.WaitOne();
80      TaskData result;
81      try {
82        if (abort) return null;
83        result = ServiceLocator.Instance.CallHiveService(s => s.GetTaskData(task.Id));
84      } finally {
85        downloadSemaphore.Release();
86      }
87      return new Tuple<Task, TaskData>(task, result);
88    }
89
90    protected Tuple<Task, T> DeserializeTask(Tuple<Task, TaskData> taskData) {
91      deserializeSemaphore.WaitOne();
92      try {
93        if (abort || taskData.Item2 == null || taskData.Item1 == null) return null;
94        var deserializedJob = PersistenceUtil.Deserialize<T>(taskData.Item2.Data);
95        taskData.Item2.Data = null; // reduce memory consumption.
96        return new Tuple<Task, T>(taskData.Item1, deserializedJob);
97      } finally {
98        deserializeSemaphore.Release();
99      }
100    }
101
102    private void TaskScheduler_UnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs e) {
103      e.SetObserved(); // avoid crash of process because task crashes. first exception found is handled in Results property
104      OnExceptionOccured(new HiveException("Unobserved Exception in ConcurrentTaskDownloader", e.Exception));
105    }
106
107    public event EventHandler<EventArgs<Exception>> ExceptionOccured;
108    private void OnExceptionOccured(Exception exception) {
109      var handler = ExceptionOccured;
110      if (handler != null) handler(this, new EventArgs<Exception>(exception));
111    }
112  }
113}
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