C++11并发与多线程笔记（10） future其他成员函数、shared_future、atomic

1、std::future 的成员函数

1.1 std::future_status

status = result.wait_for(std::chrono::seconds(几秒));

卡住当前流程，等待std::async()的异步任务运行一段时间，然后返回其状态std::future_status。如果std::async()的参数是std::launch::deferred（延迟执行），则不会卡住主流程。
std::future_status是枚举类型，表示异步任务的执行状态。类型的取值有

• std::future_status::timeout
• std::future_status::ready
• std::future_status::deferred

#include <iostream>
#include <future>
using namespace std;
 
int mythread() {
   
	cout << "mythread() start" << "threadid = " << std::this_thread::get_id() << endl;
	std::chrono::milliseconds dura(5000);
	std::this_thread::sleep_for(dura);
	cout << "mythread() end" << "threadid = " << std::this_thread::get_id() << endl;
	return 5;
}

int main() {
   
	cout << "main" << "threadid = " << std::this_thread::get_id() << endl;
	std::future<int> result = std::async(mythread);
	cout << "continue........" << endl;
	//cout << result1.get() << endl; //卡在这里等待mythread()执行完毕，拿到结果
	//等待6秒
    std::future_status status = result.wait_for(std::chrono::seconds(6));
	if (status == std::future_status::timeout) {
   
		//超时：表示线程还没有执行完
		cout << "超时了，线程还没有执行完" << endl;
	}else if(status==std::future_status::ready){
   
		cout<<"线程成功执行完毕，返回"<<endl;
		cout<<result.get()<,endl;
	}else if(status==std::future_status::deferred){