strategy_scheduler.h

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/* -*- C++ -*- */
// Strategy_Scheduler.h,v 1.19 2003/07/21 23:51:33 dhinton Exp
//
// ============================================================================
//
// = LIBRARY
//    sched
//
// = FILENAME
//    Strategy_Scheduler.h
//
// = CREATION DATE
//    22 December 1997
//
// = AUTHOR
//    Chris Gill
//
// ============================================================================

#ifndef STRATEGY_SCHEDULER_H
#define STRATEGY_SCHEDULER_H
#include /**/ "ace/pre.h"

#include "DynSched.h"

// forward declaration of the abstract base class for scheduler strategies
class ACE_Scheduler_Strategy;

/////////////////////////////////
// Strategized scheduler class //
/////////////////////////////////

class TAO_RTSched_Export ACE_Strategy_Scheduler : public ACE_DynScheduler
  // = TITLE
  //    ACE_Strategy_Scheduler
  //
  // = DESCRIPTION
  //    Strategized scheduler implementation.  Provides an implementation
  //    of all strategy specific scheduling mechanisms, which relies on the
  //    methods of the associated strategy class.
{
// public interface
public:

  ACE_Strategy_Scheduler (ACE_Scheduler_Strategy &strategy);
    // = Constructor.

  virtual ~ACE_Strategy_Scheduler ();
    // = Virtual destructor.

  status_t assign_priorities (
    Dispatch_Entry **dispatches, u_int count,
    ACE_Unbounded_Set<RtecScheduler::Scheduling_Anomaly *> &anomaly_set);
    // = Assigns priorities to the sorted dispatch schedule,
    //   according to the strategy's priority comparison operator.

  status_t assign_subpriorities (
    Dispatch_Entry **dispatches, u_int count,
    ACE_Unbounded_Set<RtecScheduler::Scheduling_Anomaly *> &anomaly_set);
    // = Assigns dynamic and static sub-priorities to the sorted dispatch
    //   schedule, according to the strategy's subpriority comparisons.

  virtual Preemption_Priority minimum_critical_priority ();
    // = Determine the minimum critical priority number.

private:

  virtual status_t schedule_timeline_entry (Dispatch_Entry &dispatch_entry,
                                            ACE_Unbounded_Queue <Dispatch_Entry *>
                                              &reschedule_queue);
    // = Schedules a dispatch entry into the timeline being created.

  virtual status_t sort_dispatches (Dispatch_Entry **dispatches, u_int count);
    // = Sets up the schedule in the order generated by the strategy.

  ACE_Scheduler_Strategy &strategy_;
    // = Strategy for comparing and sorting dispatch entries.

  ACE_UNIMPLEMENTED_FUNC (ACE_Strategy_Scheduler (const ACE_Strategy_Scheduler &))
  ACE_UNIMPLEMENTED_FUNC (ACE_Strategy_Scheduler &operator= (
    const ACE_Strategy_Scheduler &))
};



////////////////////////////////////////
// Factory for strategized schedulers //
////////////////////////////////////////

template <class STRATEGY>
class ACE_Strategy_Scheduler_Factory
  // = TITLE
  //    ACE_Strategy_Scheduler_Factory
  //
  // = DESCRIPTION
  //    Provides a type parameterized factory method that constructs
  //    and returns a scheduler that uses the given scheduling strategy
{
public:

        static ACE_Strategy_Scheduler * create (RtecScheduler::Preemption_Priority_t minimum_critical_priority);
    // = Constructs and returns a scheduler strategized with
    //   an instance of the the parameterized strategy type.
};


//////////////////////////
// Scheduler Strategies //
//////////////////////////

class TAO_RTSched_Export ACE_Scheduler_Strategy
  // = TITLE
  //    ACE_Scheduler_Strategy
  //
  // = DESCRIPTION
  //    Abstract Base Class for scheduling strategies: each derived class
  //    must define an ordering strategy for dispatch entries based on a
  //    specific scheduling algorithm.
{
public:

  ACE_Scheduler_Strategy (ACE_DynScheduler::Preemption_Priority minimum_critical_priority = 0);
  // = Constructor.

  virtual int priority_comp (const Dispatch_Entry &first_entry,
                             const Dispatch_Entry &second_entry) = 0;
    // = Compares two dispatch entries in strategy specific high to low
    //   priority ordering: returns -1 if the first Dispatch_Entry is greater
    //   in the order, 0 if they are equivalent, or 1 if the second
    //   Dispatch_Entry is greater in the order.

  virtual void sort (Dispatch_Entry **dispatch_entries,
                     u_int count) = 0;
    // = Sorts the dispatch entry link pointer array according to
    //   the specific sort order defined by the strategy.

  virtual ACE_DynScheduler::Preemption_Priority minimum_critical_priority ();
    // = Determines the minimum critical priority number.

  virtual int dynamic_subpriority_comp (const Dispatch_Entry &first_entry,
                                        const Dispatch_Entry &second_entry) = 0;
    // = Compares two dispatch entries in strategy specific high to low
    //   dynamic subpriority ordering: returns -1 if the first Dispatch_Entry
    //   is greater in the order, 0 if they are equivalent, or 1 if the
    //   second Dispatch_Entry is greater in the order.

    virtual long dynamic_subpriority (Dispatch_Entry &entry,
                                      RtecScheduler::Time current_time) = 0;
    // = Returns a dynamic subpriority value
    //   for the given timeline entry at the current time.

  virtual int static_subpriority_comp (const Dispatch_Entry &first_entry,
                                       const Dispatch_Entry &second_entry);
    // = Provides a lowest level ordering based first on importance
    // (descending), and then on the dependency topological sort finishing
    // time (ascending).

  virtual ACE_DynScheduler::Dispatching_Type
    dispatch_type (const Dispatch_Entry &entry) = 0;
    // = Provide the dispatching queue type for the given dispatch entry.

protected:

  int sort_comp (const Dispatch_Entry &first_entry,
                 const Dispatch_Entry &second_entry);
    // = Compares two dispatch entries using the specific priority, dynamic
    //   subpriority, and static subpriority method definitions provided by
    //   the derived strategy class to produce the strategy specific sort
    //   ordering: returns -1 if the first Dispatch_Entry is greater in the
    //   order, 0 if they are equivalent, or 1 if the second Dispatch_Entry is
    //   greater in the order.  This is an example of the Template Method
    //   pattern (and also of Pree's Unification Metapattern), in which
    //   derived classes provide  definitions of the methods on which the
    //   sort_comp Template Method relies.

  ACE_DynScheduler::Preemption_Priority minimum_critical_priority_;
    // = The minimum critical priority number for the strategy.
};



class TAO_RTSched_Export ACE_MUF_Scheduler_Strategy : public ACE_Scheduler_Strategy
  // = TITLE
  //    ACE_MUF_Scheduler_Strategy
  //
  // = DESCRIPTION
  //    Defines "schedule" method using Maximum Urgency First
  //    scheduling algorithm.
{
public:

  ACE_MUF_Scheduler_Strategy (ACE_DynScheduler::Preemption_Priority minimum_critical_priority = 0);
    // = Constructor.

  virtual ~ACE_MUF_Scheduler_Strategy ();
  // = Virtual destructor.

  static ACE_MUF_Scheduler_Strategy *instance ();
    // = Returns an instance of the strategy.

  virtual int priority_comp (const Dispatch_Entry &first_entry,
                             const Dispatch_Entry &second_entry);
    // = Compares two dispatch entries by maximum criticality: returns -1 if
    //   the first Dispatch_Entry is greater in the order, 0 if they're
    //   equivalent, or 1 if the second Dispatch_Entry is greater in the order.

  virtual void sort (Dispatch_Entry **dispatch_entries,
                     u_int count);
    // = Sorts the dispatch entry link pointer array
    //   in descending urgency order.

  virtual ACE_DynScheduler::Preemption_Priority minimum_critical_priority ();
    // = Determines the minimum critical priority number.

  virtual ACE_DynScheduler::Dispatching_Type
    dispatch_type (const Dispatch_Entry &entry);
    // = Provides the dispatching queue type for the given dispatch entry.

protected:

    virtual long dynamic_subpriority (Dispatch_Entry &entry,
                                      RtecScheduler::Time current_time);
    // = Returns a dynamic subpriority value at the current time for
    //   the given timeline entry: if the operation has
    //   non-negative laxity, then the value is positive, and a lower
    //   laxity gives a higher dynamic subpriority; if the operation
    //   has negative laxity, the value is the (negative) laxity value.

  virtual int dynamic_subpriority_comp (
    const Dispatch_Entry &first_entry,
    const Dispatch_Entry &second_entry);
    // = Orders two dispatch entries by ascending laxity: returns -1 if the
    //   first Dispatch_Entry is greater in the order, 0 if they're equivalent,
    //   1 if the second Dispatch_Entry is greater in the order.

private:

    // = Comparison function to pass to qsort: calls instance ()->sort_comp ().
#if defined (ACE_HAS_WINCE)
  static int _cdecl sort_function (void *arg1, void *arg2);
#else
  static int sort_function (void *arg1, void *arg2);
#endif  // ACE_HAS_WINCE

  static ACE_MUF_Scheduler_Strategy *instance_;
    // Instance of the strategy.
};


class TAO_RTSched_Export ACE_RMS_Scheduler_Strategy : public ACE_Scheduler_Strategy
  // = TITLE
  //    ACE_RMS_Scheduler_Strategy