scheduler.h

/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2017 John Wellbelove
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions :
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/
 
#ifndef ETL_SCHEDULER_INCLUDED
#define ETL_SCHEDULER_INCLUDED
 
#include "platform.h"
#include "error_handler.h"
#include "exception.h"
#include "function.h"
#include "nullptr.h"
#include "task.h"
#include "type_traits.h"
#include "vector.h"
 
#include <stdint.h>
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class scheduler_exception : public etl::exception
  {
  public:
 
    scheduler_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : etl::exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class scheduler_no_tasks_exception : public etl::scheduler_exception
  {
  public:
 
    scheduler_no_tasks_exception(string_type file_name_, numeric_type line_number_)
      : etl::scheduler_exception(ETL_ERROR_TEXT("scheduler:no tasks", ETL_SCHEDULER_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class scheduler_null_task_exception : public etl::scheduler_exception
  {
  public:
 
    scheduler_null_task_exception(string_type file_name_, numeric_type line_number_)
      : etl::scheduler_exception(ETL_ERROR_TEXT("scheduler:null task", ETL_SCHEDULER_FILE_ID"B"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class scheduler_too_many_tasks_exception : public etl::scheduler_exception
  {
  public:
 
    scheduler_too_many_tasks_exception(string_type file_name_, numeric_type line_number_)
      : etl::scheduler_exception(ETL_ERROR_TEXT("scheduler:too many tasks", ETL_SCHEDULER_FILE_ID"C"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  struct scheduler_policy_sequential_single
  {
    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
    {
      bool idle = true;
 
      for (size_t index = 0UL; index < task_list.size(); ++index)
      {
        etl::task& task = *(task_list[index]);
 
        if (task.task_request_work() > 0)
        {
          task.task_process_work();
          idle = false;
        }
      }
 
      return idle;
    }
  };

  ETL_DEPRECATED_REASON("Misspelt class name") typedef scheduler_policy_sequential_single scheduler_policy_sequencial_single;
 
  //***************************************************************************
  //***************************************************************************
  struct scheduler_policy_sequential_multiple
  {
    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
    {
      bool idle = true;
 
      for (size_t index = 0UL; index < task_list.size(); ++index)
      {
        etl::task& task = *(task_list[index]);
 
        while (task.task_request_work() > 0)
        {
          task.task_process_work();
          idle = false;
        }
      }
 
      return idle;
    }
  };

  ETL_DEPRECATED
  typedef scheduler_policy_sequential_multiple scheduler_policy_sequencial_multiple;
 
  //***************************************************************************
  //***************************************************************************
  struct scheduler_policy_highest_priority
  {
    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
    {
      bool idle = true;
 
      size_t index = 0UL;
      while (index < task_list.size())
      {
        etl::task& task = *(task_list[index]);
 
        if (task.task_request_work() > 0)
        {
          task.task_process_work();
          idle = false;
          break;
        }
        else
        {
          ++index;
        }
      }
 
      return idle;
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  struct scheduler_policy_most_work
  {
    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
    {
      bool idle = true;
 
      size_t   most_index = 0UL;
      uint32_t most_work  = 0UL;
 
      for (size_t index = 0UL; index < task_list.size(); ++index)
      {
        etl::task& task = *(task_list[index]);
 
        uint32_t n_work = task.task_request_work();
 
        if (n_work > most_work)
        {
          most_index = index;
          most_work  = n_work;
          idle       = false;
        }
      }
 
      if (!idle)
      {
        task_list[most_index]->task_process_work();
      }
 
      return idle;
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class ischeduler
  {
  public:
 
    //*******************************************
    // Virtuals.
    //*******************************************
    virtual void start() = 0;
 
    virtual ~ischeduler() {}
 
    //*******************************************
    //*******************************************
    void set_idle_callback(etl::ifunction<void>& callback)
    {
      p_idle_callback = &callback;
    }
 
    //*******************************************
    //*******************************************
    void set_watchdog_callback(etl::ifunction<void>& callback)
    {
      p_watchdog_callback = &callback;
    }
 
    //*******************************************
    //*******************************************
    void set_scheduler_running(bool scheduler_running_)
    {
      scheduler_running = scheduler_running_;
    }
 
    //*******************************************
    //*******************************************
    bool scheduler_is_running() const
    {
      return scheduler_running;
    }
 
    //*******************************************
    //*******************************************
    void exit_scheduler()
    {
      scheduler_exit = true;
    }
 
    //*******************************************
    //*******************************************
    void add_task(etl::task& task)
    {
      ETL_ASSERT(!task_list.full(), ETL_ERROR(etl::scheduler_too_many_tasks_exception));
 
      if (!task_list.full())
      {
        typename task_list_t::iterator itask = etl::upper_bound(task_list.begin(), task_list.end(), task.get_task_priority(), compare_priority());
 
        task_list.insert(itask, &task);
 
        task.on_task_added();
      }
    }
 
    //*******************************************
    //*******************************************
    template <typename TSize>
    void add_task_list(etl::task** p_tasks, TSize size)
    {
      for (TSize i = 0; i < size; ++i)
      {
        ETL_ASSERT((p_tasks[i] != ETL_NULLPTR), ETL_ERROR(etl::scheduler_null_task_exception));
        add_task(*(p_tasks[i]));
      }
    }
 
  protected:
 
    //*******************************************
    //*******************************************
    ischeduler(etl::ivector<etl::task*>& task_list_)
      : scheduler_running(false)
      , scheduler_exit(false)
      , p_idle_callback(ETL_NULLPTR)
      , p_watchdog_callback(ETL_NULLPTR)
      , task_list(task_list_)
    {
    }
 
    bool                  scheduler_running;
    bool                  scheduler_exit;
    etl::ifunction<void>* p_idle_callback;
    etl::ifunction<void>* p_watchdog_callback;
 
  private:
 
    //*******************************************
    // Used to order tasks in descending priority.
    //*******************************************
    struct compare_priority
    {
      bool operator()(etl::task_priority_t priority, etl::task* ptask) const
      {
        return priority > ptask->get_task_priority();
      }
    };
 
    typedef etl::ivector<etl::task*> task_list_t;
    task_list_t&                     task_list;
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename TSchedulerPolicy, size_t MAX_TASKS_>
  class scheduler
    : public etl::ischeduler
    , protected TSchedulerPolicy
  {
  public:
 
    enum
    {
      MAX_TASKS = MAX_TASKS_,
    };
 
    scheduler()
      : ischeduler(task_list)
    {
    }
 
    //*******************************************
    //*******************************************
    void start()
    {
      ETL_ASSERT(task_list.size() > 0, ETL_ERROR(etl::scheduler_no_tasks_exception));
 
      scheduler_running = true;
 
      while (!scheduler_exit)
      {
        if (scheduler_running)
        {
          bool idle = TSchedulerPolicy::schedule_tasks(task_list);
 
          if (p_watchdog_callback)
          {
            (*p_watchdog_callback)();
          }
 
          if (idle && p_idle_callback)
          {
            (*p_idle_callback)();
          }
        }
      }
    }
 
  private:
 
    typedef etl::vector<etl::task*, MAX_TASKS> task_list_t;
    task_list_t                                task_list;
  };
} // namespace etl
 
#endif