C++实现精确延时的多种方法与性能对比

#include <chrono>
#include <thread>

void preciseDelay(int milliseconds) {
    auto start = std::chrono::high_resolution_clock::now();
    while (true) {
        auto now = std::chrono::high_resolution_clock::now();
        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start).count();
        if (elapsed >= milliseconds) {
            break;
        }
        std::this_thread::sleep_for(std::chrono::microseconds(100)); // 减少CPU占用
    }
}

#include <windows.h>

void preciseDelayWin(int milliseconds) {
    // 提高系统定时器精度(1ms)
    TIMECAPS tc;
    timeGetDevCaps(&tc, sizeof(TIMECAPS));
    timeBeginPeriod(tc.wPeriodMin);
    
    LARGE_INTEGER frequency;
    LARGE_INTEGER start;
    LARGE_INTEGER end;
    
    QueryPerformanceFrequency(&frequency);
    QueryPerformanceCounter(&start);
    
    do {
        QueryPerformanceCounter(&end);
    } while ((end.QuadPart - start.QuadPart) * 1000 / frequency.QuadPart < milliseconds);
    
    timeEndPeriod(tc.wPeriodMin);
}

#include <time.h>

void preciseDelayLinux(int milliseconds) {
    struct timespec ts;
    ts.tv_sec = milliseconds / 1000;
    ts.tv_nsec = (milliseconds % 1000) * 1000000;
    
    int res;
    do {
        res = nanosleep(&ts, &ts);
    } while (res != 0);
}

#include <chrono>

void busyWaitDelay(int milliseconds) {
    auto start = std::chrono::high_resolution_clock::now();
    while (true) {
        auto now = std::chrono::high_resolution_clock::now();
        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start).count();
        if (elapsed >= milliseconds) {
            break;
        }
    }
}

#include <QElapsedTimer>
#include <QThread>

void qtPreciseDelay(int milliseconds) {
    QElapsedTimer timer;
    timer.start();
    while (timer.elapsed() < milliseconds) {
        QThread::usleep(100); // 减少CPU占用
    }
}

#include <iostream>
#include <chrono>
#include <thread>

int main() {
    for (int i = 0; i < 10; i++) {
        auto start = std::chrono::high_resolution_clock::now();
        
        // 你的任务代码
        std::cout << "Task " << i << " executed at " 
                  << std::chrono::system_clock::now().time_since_epoch().count() 
                  << " ns" << std::endl;
        
        // 精确延时500ms
        auto end = std::chrono::high_resolution_clock::now();
        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
        if (elapsed < 500) {
            std::this_thread::sleep_for(std::chrono::milliseconds(500 - elapsed));
        }
    }
    return 0;
}