c++11 stl atomic_flag 例子

测试代码-

#include <iostream>       // std::cout
#include <atomic>         // std::atomic_flag
#include <thread>         // std::thread
#include <vector>         // std::vector
#include <sstream>       // std::stringstream

using namespace std;

atomic_flag lock_stream = ATOMIC_FLAG_INIT;
stringstream stream;

void append_number(int x)
{
    while (lock_stream.test_and_set())
    {
        ;
    }

    stream << "thread #" << x <<"::get lock"<<'\n';
    this_thread::sleep_for (chrono::seconds(1));//sleep check for if over thread can get the lock
    stream << "thread #" << x<<"::release lock"<< '\n';

    lock_stream.clear();
}

int main ()
{
    std::vector<std::thread> threads;

    for (int i=1; i<=10; ++i)
    {
        threads.push_back(thread(append_number,i));//create thread
    }

    for (auto& th : threads) 
    {
        th.join();// wait thread return
    }

    cout << stream.str();

    return 0;
}

输出结果：

thread #1::get lock
thread #1::release lock
thread #9::get lock
thread #9::release lock
thread #4::get lock
thread #4::release lock
thread #8::get lock
thread #8::release lock
thread #7::get lock
thread #7::release lock
thread #10::get lock
thread #10::release lock
thread #2::get lock
thread #2::release lock
thread #6::get lock
thread #6::release lock
thread #3::get lock
thread #3::release lock
thread #5::get lock
thread #5::release lock
请按任意键继续. . .