scheduler.h

LINUX 下的 NACHOS 系统 实现系统调度的算法功能

// scheduler.h 
//  Data structures for the thread dispatcher and scheduler.
//  Primarily, the list of threads that are ready to run.
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#ifndef SCHEDULER_H
#define SCHEDULER_H

#include "copyright.h"
#include "list.h"
#include "thread.h"
#include "oneshot.h"
#include "timer.h"
#include "testcase.h"

enum SchedPolicy { 
  SCHED_FCFS,     // First-come first-served scheduling 
  SCHED_SJF,      // Shortest Job First
  SCHED_SRTN,     // Shortest Remaining Time Next
  SCHED_PRIO,     // Priority 
  SCHED_RR,       // Round Robin 
  SCHED_MQ,       // Multiple Queues 
};

// The following class defines the scheduler/dispatcher abstraction -- 
// the data structures and operations needed to keep track of which 
// thread is running, and which threads are ready but not running.

class Scheduler
{
  public:
    Scheduler();       // Initialize list of ready threads 
    ~Scheduler();      // De-allocate ready list

    void ReadyToRun(Thread* thread); // Thread can be dispatched.
    Thread* FindNextToRun();  // Dequeue first thread on the ready 
                              // list, if any, and return thread.
    bool ShouldISwitch(Thread* oldThread, Thread* newThread);
    void Run(Thread* nextThread); // Cause nextThread to start running
    void Print();  // Print contents of ready list
    void Suspend(Thread *thread);
    void Resume(Thread *thread);
    void SetSchedPolicy(SchedPolicy pol);

    SchedPolicy getSchedPolicy()        // Get the scheduling policy
    {
      return policy;
    }                               

    void InterruptHandler( int dummy );

  private:
    SchedPolicy policy;            // scheduling policy to be used
    List<Thread *> *readyList;     // queue of threads that are ready to run,
                                   // but not running
    List<Thread *> *suspendedList; // List of suspended threads.
    Timer * ptimer;

    // MP1
    int currentRRnum;
};

#endif // SCHEDULER_H