std::packaged_task::make_ready_at_thread_exit
From cppreference.com
< cpp | thread | packaged task
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.
Parameters
args | - | the parameters to pass on invocation of the stored task |
Return value
(none)
Exceptions
std::future_error on the following error conditions:
- The stored task has already been invoked. The error category is set to
promise_already_satisfied
. - *this has no shared state. The error category is set to no_state.
Example
Run this code
#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
See also
executes the function (public member function) |