engine.cpp

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <atomic>

#ifdef _WIN32
#include <windows.h>
#else
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <cstring>
#endif

using namespace std;

struct alignas(10) StockData {
    // Need to add all parameters (expecting 10 now)
    char ticker[16];
    double price;
    double pe_ratio;
    double pb_ratio;
    double roce;
    double debt_to_equity;
    double eps_growth;
    double score;
};

struct MarketState {
    atomic<int> sync_flag;
    int _padding;
    StockData universe[6000];
};

double CalculateScore(const StockData& stock) {
    // Implement the actual weighted math here. 
    // To achieve the low-latency requirement, structure this logic using SIMD intrinsics 
    // or ensure the math is entirely branchless so the compiler auto-vectorizes it.

}

bool CompareStocks(const StockData& a, const StockData& b) {
    return a.score > b.score;
}

// detect churn function to be implemented.

int main() {
    int fd = open("shm", O_RDWR | O_CREAT, 0666);
    ftruncate(fd, sizeof(marketstate));
    void* ptr = mmap(0, sizeof(marketstate), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    marketstate* shm = (marketstate*)ptr;

    vector<stockdata> pool(6000);
    vector<stockdata> prev(50);
    vector<stockdata> cur(50);

    while (true) {
        // Implement memory barriers or std::atomic operations around this flag read/write process. 
        // If we rely on standard integers, compiler optimizations might skip reading the RAM, leading to missed updates.
        if (shm->sf == 2) {
            for (int i = 0; i < 6000; ++i) {
                pool[i] = shm->u[i];
                pool[i].sc = calc(pool[i]);
            }

            shm->sf = 0;

            partial_sort(pool.begin(), pool.begin() + 50, pool.end(), comp);

            for (int i = 0; i < 50; ++i) {
                cur[i] = pool[i];
            }

            for (int i = 0; i < 50; ++i) {
                bool f = false;
                for (int j = 0; j < 50; ++j) {
                    if (strcmp(prev[i].t, cur[j].t) == 0) {
                        f = true;
                        break;
                    }
                }
                // Upgrade this section. 
                // When f == false (a dropout is detected), we must calculate why it dropped out 
                // (e.g., comparing its previous ROCE to its current ROCE) 
                // and write a structured alert payload to a secondary output buffer or file for the reporting layer to process.
                if (f == false) {
                    // Currently, it just prints the missing ticker to standard output.
                    cout << prev[i].t << "\n";
                }
            }

            for (int i = 0; i < 50; ++i) {
                prev[i] = cur[i];
            }
        }
    }
    return 0;
}