std::packaged_task<R(Args...)>::make_ready_at_thread_exit

 
 
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void make_ready_at_thread_exit( ArgTypes... args );
(C++11 起)

以转发的 args 为参数调用存储的任务。任务返回值或任何抛出的异常被存储于 *this 的共享状态。

仅在当前线程退出,并销毁所有线程局域存储期对象后,才令共享状态就绪。

参数

args - 调用时传递给存储任务的参数

返回值

(无)

异常

遇到下列条件时为 std::future_error

示例

#include <future>
#include <iostream>
#include <chrono>
#include <thread>
#include <functional>
#include <utility>
 
void worker(std::future<void>& output)
{
    std::packaged_task<void(bool&)> my_task{ [](bool& done) { done=true; } };
 
    auto result = my_task.get_future();
 
    bool done = false;
 
    my_task.make_ready_at_thread_exit(done); // 立即执行任务
 
    std::cout << "worker: done = " << std::boolalpha << done << std::endl;
 
    auto status = result.wait_for(std::chrono::seconds(0));
    if (status == std::future_status::timeout)
        std::cout << "worker: result is not ready yet" << std::endl;
 
    output = std::move(result);
}
 
 
int main()
{
    std::future<void> result;
 
    std::thread{worker, std::ref(result)}.join();
 
    auto status = result.wait_for(std::chrono::seconds(0));
    if (status == std::future_status::ready)
        std::cout << "main: result is ready" << std::endl;
}

输出:

worker: done = true
worker: result is not ready yet
main: result is ready

参阅

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