#include <iostream>
#include <future>
#include <thread>

using namespace std;
using namespace std::chrono;

void WaitForMilkTea(future<int>& future)
{
	/*其中獲取future結(jié)果有三種方式
	 1、auto value = future.get()    get()方法會阻塞等待異步操作結(jié)束并返回結(jié)果
	 2、std::future_status  方式判斷狀態(tài) 有deferred、timeout、ready三種狀態(tài)
	 3、可以
	*/

//future_status方法
#if 0
	std::future_status status;
	do {
		status = future.wait_for(std::chrono::milliseconds(500));
		if (status == std::future_status::deferred) {
			std::cout << "deferred!!!" << std::endl; //異步操作還沒開始
		} else if (status == std::future_status::timeout) {
			std::cout << "timeout!!!" << std::endl; //異步操作超時
		} else if (status == std::future_status::ready) {
			std::cout << "ready!!!" << std::endl; //異步操作已經(jīng)完成
		}
	} while (status != std::future_status::ready);
     
	//通過判斷future_status狀態(tài)為ready時才通過get()獲取值
	auto notice = future.get();
	std::cout << "WaitForMilkTea receive value:" << notice << std::endl;
#endif

//get()方法
#if 0
	auto notice = future.get();   //get阻塞等待直到異步處理結(jié)束返回值
	std::cout << "WaitForMilkTea receive value:" << notice << std::endl;
#endif

//wait()方法
	future.wait(); //和get()區(qū)別是wait只等待異步操作完成，沒有返回值
	auto notice = future.get();
	std::cout << "WaitForMilkTea receive value:" << notice << std::endl;
}

void MakeTea(promise<int>& promise)
{
	//do something 這里先睡眠5s
	std::this_thread::sleep_for(std::chrono::seconds(5));
	promise.set_value(1);
	std::this_thread::sleep_for(std::chrono::seconds(10));
	std::cout << "MakeTea Thread quit!!!" << std::endl;
}

int main()
{
	promise<int> pNotice;
	//獲取與promise相關(guān)聯(lián)的future
	future<int> pFuture = pNotice.get_future();

	thread Customer(WaitForMilkTea, ref(pFuture));
	thread Worker(MakeTea, ref(pNotice));

	Customer.join();
	Worker.join();
}

#include <iostream>
#include <future>
#include <thread>

using namespace std;
using namespace std::chrono;

void futureHandleEntry(std::shared_future<int>& future) 
{
	if (future.valid()) {
		future.wait();
		std::cout << "thread:[" << std::this_thread::get_id() << "] value=" << future.get() << std::endl;
		std::cout << "thread:[" << std::this_thread::get_id() << "] quit!!!" << std::endl;
	}
	else {
		std::cout << "future is invalid!!!" << std::endl;
	}
}

int main()
{
    std::promise<int> promise;
	//獲取shared_future用于多線程訪問異步操作結(jié)果
	std::shared_future<int> future = promise.get_future();

	std::thread t1(&futureHandleEntry, ref(future));
	std::thread t2(&futureHandleEntry, ref(future));
	std::thread t3(&futureHandleEntry, ref(future));

	std::cout << "main thread running!!!" << std::endl;
	//主線程sleep5s后去set_value
	std::this_thread::sleep_for(std::chrono::seconds(5));
	promise.set_value(10);

	t1.join();
	t2.join();
	t3.join();
}

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

using namespace std;

void threadEntry(std::future<int>& future)
{
	try {
		auto value = future.get();
		std::cout << "value=" << value << std::endl;
	}
	catch (std::future_error& error) {
		std::cerr << error.code() << "\n" << error.what() << std::endl;
	}
}
int main()
{
	std::promise<int> promise;
	std::future<int> future = promise.get_future();

	std::thread t1(threadEntry, ref(future));
	/*主線程promise多次調(diào)用set_value會拋出future_error異常
	*/
	std::this_thread::sleep_for(std::chrono::seconds(2));
	promise.set_value(1); 
	promise.set_value(1);

	t1.join();
}

#include <iostream> // std::cout, std::endl
#include <thread>   // std::thread
#include <future>   // std::promise, std::future
#include <chrono>   // seconds
using namespace std::chrono;

void read(std::future<int> future) {
    try {
        future.get();
    } catch(std::future_error &e) {
        std::cerr << e.code() << "\n" << e.what() << std::endl;
    }
}

int main() {
    std::thread thread;
    {
        // 如果promise不設(shè)置任何值
        // 則在promise析構(gòu)時會自動設(shè)置為future_error
        // 這會造成future.get拋出該異常
        std::promise<int> promise;
        thread = std::thread(read, promise.get_future());
   }
    thread.join();

    return 0;
}

#include <iostream>
 #include <future>
 #include <thread>
 #include <exception>  // std::make_exception_ptr
 #include <stdexcept>  // std::logic_error
 
void catch_error(std::future<void> &future) {
    try {
       future.get();
    } catch (std::logic_error &e) {
       std::cerr << "logic_error: " << e.what() << std::endl;
   }
}

int main() {
    std::promise<void> promise;
    std::future<void> future = promise.get_future();

    std::thread thread(catch_error, std::ref(future));
    // 自定義異常需要使用make_exception_ptr轉(zhuǎn)換一下
    promise.set_exception(
       std::make_exception_ptr(std::logic_error("caught")));

      thread.join();
     return 0;
}

// std::promise::set_exception函數(shù)原型
2void set_exception(std::exception_ptr p);