Home | History | Annotate | Download | only in base 
      1 /*
      2  * libjingle
      3  * Copyright 2004--2006, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef TALK_BASE_TASKRUNNER_H__
     29 #define TALK_BASE_TASKRUNNER_H__
     30 
     31 #include <vector>
     32 
     33 #include "talk/base/basictypes.h"
     34 #include "talk/base/sigslot.h"
     35 #include "talk/base/taskparent.h"
     36 
     37 namespace talk_base {
     38 class Task;
     39 
     40 const int64 kSecToMsec = 1000;
     41 const int64 kMsecTo100ns = 10000;
     42 const int64 kSecTo100ns = kSecToMsec * kMsecTo100ns;
     43 
     44 class TaskRunner : public TaskParent, public sigslot::has_slots<> {
     45  public:
     46   TaskRunner();
     47   virtual ~TaskRunner();
     48 
     49   virtual void WakeTasks() = 0;
     50 
     51   // Returns the current time in 100ns units.  It is used for
     52   // determining timeouts.  The origin is not important, only
     53   // the units and that rollover while the computer is running.
     54   //
     55   // On Windows, GetSystemTimeAsFileTime is the typical implementation.
     56   virtual int64 CurrentTime() = 0 ;
     57 
     58   void StartTask(Task *task);
     59   void RunTasks();
     60   void PollTasks();
     61 
     62   void UpdateTaskTimeout(Task *task, int64 previous_task_timeout_time);
     63 
     64 #ifdef _DEBUG
     65   bool is_ok_to_delete(Task* task) {
     66     return task == deleting_task_;
     67   }
     68 
     69   void IncrementAbortCount() {
     70     ++abort_count_;
     71   }
     72 
     73   void DecrementAbortCount() {
     74     --abort_count_;
     75   }
     76 #endif
     77 
     78   // Returns the next absolute time when a task times out
     79   // OR "0" if there is no next timeout.
     80   int64 next_task_timeout() const;
     81 
     82  protected:
     83   // The primary usage of this method is to know if
     84   // a callback timer needs to be set-up or adjusted.
     85   // This method will be called
     86   //  * when the next_task_timeout() becomes a smaller value OR
     87   //  * when next_task_timeout() has changed values and the previous
     88   //    value is in the past.
     89   //
     90   // If the next_task_timeout moves to the future, this method will *not*
     91   // get called (because it subclass should check next_task_timeout()
     92   // when its timer goes off up to see if it needs to set-up a new timer).
     93   //
     94   // Note that this maybe called conservatively.  In that it may be
     95   // called when no time change has happened.
     96   virtual void OnTimeoutChange() {
     97     // by default, do nothing.
     98   }
     99 
    100  private:
    101   void InternalRunTasks(bool in_destructor);
    102   void CheckForTimeoutChange(int64 previous_timeout_time);
    103 
    104   std::vector<Task *> tasks_;
    105   Task *next_timeout_task_;
    106   bool tasks_running_;
    107 #ifdef _DEBUG
    108   int abort_count_;
    109   Task* deleting_task_;
    110 #endif
    111 
    112   void RecalcNextTimeout(Task *exclude_task);
    113 };
    114 
    115 } // namespace talk_base
    116 
    117 #endif  // TASK_BASE_TASKRUNNER_H__
    118