Simulation of Disk Scheduling Algorithms Gaming Project in C++

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3 months ago

#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

class DiskScheduler {
public:
    // FCFS Algorithm
    int FCFS(const std::vector<int>& requests, int head) {
        int seek_operations = 0;
        int current_position = head;

        for (int request : requests) {
            seek_operations += std::abs(current_position - request);
            current_position = request;
        }

        return seek_operations;
    }

    // SSTF Algorithm
    int SSTF(std::vector<int> requests, int head) {
        int seek_operations = 0;
        int current_position = head;

        while (!requests.empty()) {
            auto closest = std::min_element(requests.begin(), requests.end(),
                [&current_position](int a, int b) {
                    return std::abs(a - current_position) < std::abs(b - current_position);
                });

            seek_operations += std::abs(current_position - *closest);
            current_position = *closest;
            requests.erase(closest);
        }

        return seek_operations;
    }

    // SCAN (Elevator) Algorithm
    int SCAN(std::vector<int> requests, int head, int disk_size) {
        int seek_operations = 0;
        int current_position = head;

        std::sort(requests.begin(), requests.end());
        
        // Split requests into those less than and greater than the current head position
        std::vector<int> left, right;
        for (int request : requests) {
            if (request < current_position)
                left.push_back(request);
            else
                right.push_back(request);
        }

        // Scan to the right (towards the end of the disk)
        for (int request : right) {
            seek_operations += std::abs(current_position - request);
            current_position = request;
        }

        // Then scan to the left (towards the beginning of the disk)
        if (!left.empty()) {
            seek_operations += std::abs(current_position - disk_size);
            current_position = disk_size;

            for (auto it = left.rbegin(); it != left.rend(); ++it) {
                seek_operations += std::abs(current_position - *it);
                current_position = *it;
            }
        }

        return seek_operations;
    }
};

int main() {
    DiskScheduler scheduler;
    int head, disk_size, num_requests;

    std::cout << "Enter initial head position: ";
    std::cin >> head;

    std::cout << "Enter disk size: ";
    std::cin >> disk_size;

    std::cout << "Enter number of requests: ";
    std::cin >> num_requests;

    std::vector<int> requests(num_requests);
    std::cout << "Enter the requests: ";
    for (int i = 0; i < num_requests; ++i) {
        std::cin >> requests[i];
    }

    int fcfs_seek = scheduler.FCFS(requests, head);
    int sstf_seek = scheduler.SSTF(requests, head);
    int scan_seek = scheduler.SCAN(requests, head, disk_size);

    std::cout << "Total seek operations (FCFS): " << fcfs_seek << "\n";
    std::cout << "Total seek operations (SSTF): " << sstf_seek << "\n";
    std::cout << "Total seek operations (SCAN): " << scan_seek << "\n";

    return 0;
}

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#include <iostream>

#include <vector>

#include <algorithm>

#include <cmath>

class DiskScheduler {

public:

// FCFS Algorithm

int FCFS(const std::vector<int>& requests, int head) {

int seek_operations = 0;

int current_position = head;

for (int request : requests) {

seek_operations += std::abs(current_position - request);

current_position = request;

}

return seek_operations;

}

// SSTF Algorithm

int SSTF(std::vector<int> requests, int head) {

int seek_operations = 0;

int current_position = head;

while (!requests.empty()) {

auto closest = std::min_element(requests.begin(), requests.end(),

[&current_position](int a, int b) {

return std::abs(a - current_position) < std::abs(b - current_position);

});

seek_operations += std::abs(current_position - *closest);

current_position = *closest;

requests.erase(closest);

}

return seek_operations;

}

// SCAN (Elevator) Algorithm

int SCAN(std::vector<int> requests, int head, int disk_size) {

int seek_operations = 0;

int current_position = head;

std::sort(requests.begin(), requests.end());

// Split requests into those less than and greater than the current head position

std::vector<int> left, right;

for (int request : requests) {

if (request < current_position)

left.push_back(request);

else

right.push_back(request);

}

// Scan to the right (towards the end of the disk)

for (int request : right) {

seek_operations += std::abs(current_position - request);

current_position = request;

}

// Then scan to the left (towards the beginning of the disk)

if (!left.empty()) {

seek_operations += std::abs(current_position - disk_size);

current_position = disk_size;

for (auto it = left.rbegin(); it != left.rend(); ++it) {

seek_operations += std::abs(current_position - *it);

current_position = *it;

}

return seek_operations;

}

};

int main() {

DiskScheduler scheduler;

int head, disk_size, num_requests;

std::cout << "Enter initial head position: ";

std::cin >> head;

std::cout << "Enter disk size: ";

std::cin >> disk_size;

std::cout << "Enter number of requests: ";

std::cin >> num_requests;

std::vector<int> requests(num_requests);

std::cout << "Enter the requests: ";

for (int i = 0; i < num_requests; ++i) {

std::cin >> requests[i];

}

int fcfs_seek = scheduler.FCFS(requests, head);

int sstf_seek = scheduler.SSTF(requests, head);

int scan_seek = scheduler.SCAN(requests, head, disk_size);

std::cout << "Total seek operations (FCFS): " << fcfs_seek << "\n";

std::cout << "Total seek operations (SSTF): " << sstf_seek << "\n";

std::cout << "Total seek operations (SCAN): " << scan_seek << "\n";

return 0;

}

Explanation

DiskScheduler Class:
- This class contains implementations for the FCFS, SSTF, and SCAN (Elevator) disk scheduling algorithms.
- Each algorithm is implemented as a member function returning the total number of seek operations required.
FCFS Algorithm:
- The FCFS function implements the First-Come, First-Served algorithm. It processes each request in the order received and calculates the total seek time.
- This algorithm is straightforward but can lead to high seek times if requests are far apart.
SSTF Algorithm:
- The SSTF function implements the Shortest Seek Time First algorithm. It selects the request that is closest to the current head position, minimizing seek time at each step.
- This algorithm reduces seek time but can cause starvation for requests that are far from the current head position.
SCAN Algorithm:
- The SCAN function simulates the Elevator algorithm, where the disk arm moves in one direction, fulfilling requests until it reaches the end, then reverses direction.
- This algorithm reduces the variance in seek time and is more efficient than FCFS in most cases.
Main Function:
- The main function prompts the user for the initial head position, disk size, and a list of disk requests.
- It then calculates the total seek operations for each algorithm and displays the results.

Usage

Initial Head Position: The starting position of the disk head.
Disk Size: The total size of the disk, which defines the maximum possible request position.
Requests: A series of disk I/O requests, each representing a position on the disk where data needs to be read or written.

Explanation

Usage

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