priorityDiscipline.cpp

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#include "priorityDiscipline.h"

#include <algorithm>
#include <vector>

#include <scheduler/process.h>
#include <scheduler/queue.h>

using namespace Scheduler;


std::shared_ptr<Process> PriorityDiscipline::selectNextTask(Queue *readyQueue, std::shared_ptr<Process> running, unsigned int)
{
    updatePriorities(readyQueue, running);

    int highestPriority = std::numeric_limits<int>::min();
    std::shared_ptr<Process> candidate = running;
    if (running != nullptr)
        highestPriority = candidate->getPriority();
    for (auto it = readyQueue->begin() ; it != readyQueue->end(); it++)
    {
        if ((*it)->getPriority() > highestPriority)
        {
            candidate = (*it);
            highestPriority = candidate->getPriority();
        }
    }
    return candidate;
}

bool PriorityDiscipline::preempts(TriggeringEvent trigger)
{
    return (trigger == newprocess || trigger == ready);
}


void PriorityDiscipline::updatePriorities(Queue * readyQueue, std::shared_ptr<Process>  running)
{
    std::vector<std::shared_ptr<Process> > ranking(readyQueue->size());
    unsigned int i = 0;
    for (auto it = readyQueue->begin(); it != readyQueue->end(); it++, i++)
    {
        ranking[i] = (*it);
    }
    if (running != nullptr)
        ranking.push_back(running);
    std::sort(ranking.begin(), ranking.end(), getComparator());
    for (unsigned int i = 0; i < ranking.size(); i++)
        ranking[i]->setPriority(ranking.size()-i);
    
}

PriorityDiscipline::ComparatorPointer PriorityDiscipline::getComparator()
{
    return [](std::shared_ptr<Process> a, std::shared_ptr<Process> b){return a->getPriority() > b->getPriority();};
}