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现代C++ [4]: std::lock_guard

 11 months ago
source link: https://no5-aaron-wu.github.io/2023/02/16/cpp-modern-4-LockGuard/
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旭穹の陋室

现代C++ [4]: std::lock_guard

发表于2023-02-16|更新于2023-05-05|语言
阅读量:3

std::lock_guard类是C++11新加入的特性，它是一个mutex包装器，提供了一种方便的RAII风格机制，该包装器在构造时自动绑定传入的mutex并加锁，在其析构函数中解锁，从而实现在作用域块的持续时间内拥有mutex而无需手动解锁，从而大大减少了死锁的可能性。

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

int g_i = 0;
std::mutex g_i_mutex;  // protects g_i

void safe_increment()
{
    const std::lock_guard<std::mutex> lock(g_i_mutex);
    ++g_i;

std::cout << "g_i: " << g_i << "; in thread #"
              << std::this_thread::get_id() << '\n';

// g_i_mutex is automatically released when lock
    // goes out of scope
}

int main()
{
    std::cout << "g_i: " << g_i << "; in main()\n";

std::thread t1(safe_increment);
    std::thread t2(safe_increment);

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

std::cout << "g_i: " << g_i << "; in main()\n";
}

[1] https://en.cppreference.com/w/cpp/thread/lock_guard


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