void make_ready_at_thread_exit( ArgTypes... args ); | (since C++11) |
Calls the stored task with forwarded args as the arguments. The return value of the task or any exception thrown by it is stored in the shared state of *this.
The shared state is only made ready after the current thread exits and all objects of thread local storage duration are destroyed.
| args | - | the parameters to pass on invocation of the stored task |
(none).
std::future_error on the following error conditions:
promise_already_satisfied. *this has no shared state. The error category is set to no_state. #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); // execute task right away
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;
}Output:
worker: done = true worker: result is not ready yet main: result is ready
| executes the function (public member function) |
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