[6976] | 1 | #region License Information
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| 2 | /* HeuristicLab
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| 3 | * Copyright (C) 2002-2011 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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| 4 | *
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| 5 | * This file is part of HeuristicLab.
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| 6 | *
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| 7 | * HeuristicLab is free software: you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation, either version 3 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * HeuristicLab is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 | #endregion
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| 21 |
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| 22 | using System;
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| 23 | using System.Threading;
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| 24 | using System.Threading.Tasks;
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| 25 | using HeuristicLab.Common;
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| 26 | using HeuristicLab.Hive;
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| 27 |
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| 28 | namespace HeuristicLab.Clients.Hive {
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| 29 | /// <summary>
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| 30 | /// Downloads and deserializes jobs. It avoids too many jobs beeing downloaded or deserialized at the same time to avoid memory problems
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| 31 | /// </summary>
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| 32 | public class ConcurrentTaskDownloader<T> where T : class, ITask {
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| 33 | private bool abort = false;
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| 34 | // use semaphore to ensure only few concurrenct connections and few SerializedJob objects in memory
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| 35 | private Semaphore downloadSemaphore;
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| 36 | private Semaphore deserializeSemaphore;
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| 37 |
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| 38 | public ConcurrentTaskDownloader(int concurrentDownloads, int concurrentDeserializations) {
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| 39 | downloadSemaphore = new Semaphore(concurrentDownloads, concurrentDownloads);
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| 40 | deserializeSemaphore = new Semaphore(concurrentDeserializations, concurrentDeserializations);
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| 41 | TaskScheduler.UnobservedTaskException += new EventHandler<UnobservedTaskExceptionEventArgs>(TaskScheduler_UnobservedTaskException);
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| 42 | }
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| 43 |
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| 44 | public void DownloadTask(Task job, Action<Task, T> onFinishedAction) {
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| 45 | Task<T> task = Task<TaskData>.Factory.StartNew((x) => DownloadTask(x), job.Id)
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| 46 | .ContinueWith((x) => DeserializeTask(x.Result));
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| 47 | task.ContinueWith((x) => OnTaskFinished(job, x, onFinishedAction), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnRanToCompletion);
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| 48 | task.ContinueWith((x) => OnTaskFailed(job, x, onFinishedAction), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnFaulted);
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| 49 | }
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| 50 |
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| 51 | private void OnTaskFinished(Task job, Task<T> task, Action<Task, T> onFinishedAction) {
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| 52 | onFinishedAction(job, task.Result);
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| 53 | }
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| 54 | private void OnTaskFailed(Task job, Task<T> task, Action<Task, T> onFinishedAction) {
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| 55 | task.Exception.Flatten().Handle((e) => { return true; });
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| 56 | OnExceptionOccured(task.Exception.Flatten());
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| 57 | onFinishedAction(job, null);
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| 58 | }
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| 59 |
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| 60 | protected TaskData DownloadTask(object taskId) {
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| 61 | downloadSemaphore.WaitOne();
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| 62 | deserializeSemaphore.WaitOne();
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| 63 | TaskData result;
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| 64 | try {
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| 65 | if (abort) return null;
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| 66 | result = ServiceLocator.Instance.CallHiveService(s => s.GetTaskData((Guid)taskId));
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| 67 | }
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| 68 | finally {
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| 69 | downloadSemaphore.Release();
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| 70 | }
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| 71 | return result;
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| 72 | }
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| 73 |
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| 74 | protected T DeserializeTask(TaskData taskData) {
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| 75 | try {
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| 76 | if (abort || taskData == null) return null;
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| 77 | Task task = ServiceLocator.Instance.CallHiveService(s => s.GetTask(taskData.TaskId));
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| 78 | if (task == null) return null;
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| 79 | var deserializedJob = PersistenceUtil.Deserialize<T>(taskData.Data);
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| 80 | taskData.Data = null; // reduce memory consumption.
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| 81 | return deserializedJob;
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| 82 | }
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| 83 | finally {
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| 84 | deserializeSemaphore.Release();
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| 85 | }
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| 86 | }
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| 87 |
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| 88 | private void TaskScheduler_UnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs e) {
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| 89 | e.SetObserved(); // avoid crash of process because task crashes. first exception found is handled in Results property
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| 90 | OnExceptionOccured(new HiveException("Unobserved Exception in ConcurrentTaskDownloader", e.Exception));
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| 91 | }
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| 92 |
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| 93 | public event EventHandler<EventArgs<Exception>> ExceptionOccured;
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| 94 | private void OnExceptionOccured(Exception exception) {
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| 95 | var handler = ExceptionOccured;
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| 96 | if (handler != null) handler(this, new EventArgs<Exception>(exception));
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| 97 | }
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| 98 | }
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| 99 | }
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