std::packaged_task::reset

 

C++

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Thread support library

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lock_guard (C++11) unique_lock (C++11) shared_lock (C++14) defer_lock_ttry_to_lock_tadopt_lock_t (C++11)(C++11)(C++11)	lock (C++11) try_lock (C++11) defer_locktry_to_lockadopt_lock (C++11)(C++11)(C++11) once_flag (C++11) call_once (C++11)
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std::packaged_task

Member functions

packaged_task::packaged_task

packaged_task::~packaged_task

packaged_task::operator=

packaged_task::valid

packaged_task::swap

Getting the result

packaged_task::get_future

Execution

packaged_task::operator()

packaged_task::make_ready_at_thread_exit

packaged_task::reset

 

void reset();		(since C++11)

Resets the state abandoning the results of previous executions. New shared state is constructed.

Equivalent to *this = packaged_task(std::move(f)), where f is the stored task.

Parameters

(none)

Return value

(none)

Exceptions

• std::future_error if *this has no shared state. The error condition is set to no_state.
• std::bad_alloc if there was not enough memory for a new shared state.
• any exception thrown by the move constructor of the new packaged_task

Example

Run this code

#include <iostream>
#include <cmath>
#include <thread>
#include <future>
 
int main()
{
    std::packaged_task<int(int,int)> task([](int a, int b) {
        return std::pow(a, b);
    });
    std::future<int> result = task.get_future();
    task(2, 9);
    std::cout << "2^9 = " << result.get() << '\n';
 
    task.reset();
    result = task.get_future();
    std::thread task_td(std::move(task), 2, 10);
    task_td.join();
    std::cout << "2^10 = " << result.get() << '\n';
}

Output:

2^9 = 512
2^10 = 1024