c++如何使用互斥锁std::lock_guard和std::unique_lock_c++互斥锁RAII封装用法解析

#include <thread>
#include <mutex>
#include <iostream>

std::mutex mtx;
int shared_data = 0;

void unsafe_increment() {
    for (int i = 0; i < 100000; ++i) {
        std::lock_guard<std::mutex> lock(mtx); // 自动加锁
        ++shared_data; // 操作共享数据
    } // 离开作用域时自动解锁
}

int main() {
    std::thread t1(unsafe_increment);
    std::thread t2(unsafe_increment);

    t1.join();
    t2.join();

    std::cout << "Final value: " << shared_data << std::endl;
    return 0;
}

#include <thread>
#include <mutex>
#include <condition_variable>
#include <iostream>

std::mutex mtx;
std::condition_variable cv;
bool ready = false;

void worker_thread() {
    std::unique_lock<std::mutex> lock(mtx, std::defer_lock); // 不立即加锁

    lock.lock(); // 手动加锁
    std::cout << "Worker thread acquired the lock." << std::endl;

    while (!ready) {
        std::cout << "Waiting for notification..." << std::endl;
        lock.unlock(); // 临时释放锁
        // 模拟其他操作
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        lock.lock(); // 重新加锁
    }
}

void notifier() {
    std::this_thread::sleep_for(std::chrono::seconds(1));
    std::unique_lock<std::mutex> lock(mtx);
    ready = true;
    std::cout << "Notifying..." << std::endl;
    cv.notify_one();
}

std::unique_lock<std::mutex> lock(mtx);
cv.wait(lock, []{ return ready; }); // wait 会自动释放锁，并在唤醒后重新获取