src/AsyncFramework/IJob.h

   1 /***************************************************************************
   2  *   Copyright (C) 2009-2010 by Stefan Fuhrmann                            *
   3  *   stefanfuhrmann@alice-dsl.de                                           *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  19  ***************************************************************************/
  20
  21 #pragma once
  22
  23 namespace async
  24 {
  25
  26 // forward declaration
  27
  28 class CJobScheduler;
  29
  30 /**
  31  * Common interface to all job objects that can be handled by
  32  * \ref CJobScheduler instances.
  33  *
  34  * Jobs will be executed only once making the \ref done state
  35  * the final state of the internal state machine.
  36  */
  37
  38 class IJob
  39 {
  40 public:
  41
  42     /**
  43      * Possible values returned by \ref GetStatus().
  44      * The state machine linearly follows the value order.
  45      */
  46
  47     enum Status
  48     {
  49         waiting = 0,
  50         running = 1,
  51         suspended = 2,
  52         done = 3
  53     };
  54
  55     /// destruction
  56
  57     virtual ~IJob(void) {}
  58
  59     /// call this to put the job into the scheduler.
  60     /// If \ref transferOwnership is set, the scheduler must
  61     /// delete this instance after execution.
  62
  63     virtual void Schedule ( bool transferOwnership
  64                           , CJobScheduler* scheduler) = 0;
  65
  66     /// will be called by job execution thread.
  67
  68     virtual void Execute() = 0;
  69
  70     /// may be called by other (observing) threads.
  71     /// Please note that the information returned may already
  72     /// be outdated as soon as the function returns.
  73
  74     virtual Status GetStatus() const = 0;
  75
  76     /// Efficiently wait for instance to reach the
  77     /// \ref done \ref Status.
  78     /// If \ref inlineExecution is set, the job will be
  79     /// executed in the current thread if it is still waiting.
  80
  81     virtual void WaitUntilDone (bool inlineExecution = false) = 0;
  82
  83 private:
  84
  85     /// Called by the \ref CJobScheduler instance before
  86     /// it actually add this job to its execution list.
  87
  88     virtual void OnSchedule (CJobScheduler* scheduler) = 0;
  89
  90     /// Called by the \ref CJobScheduler instance after
  91     /// it removed this job from its execution list.
  92     /// The job must not be deleted before this function
  93     /// has been called.
  94
  95     virtual void OnUnSchedule (CJobScheduler* scheduler) = 0;
  96
  97     // callbacks are ment to be used by \ref CJobScheduler only
  98
  99     friend class CJobScheduler;
 100 };
 101
 102 }