I want to use submit to construct a function, which can be used in other threads. And In order not to be blocked, submit will return std::future, which can let me get the return value in the proper time. My code is below:
std::vector<std::function<void()>> fuctions(0);
std::vector<std::future<int>> futures(0);
template <typename Function, typename ...Args>
std::future<typename std::result_of_t<Function(Args...)>> submit(Function f, Args... args) {
using result_type = typename std::result_of_t<Function(Args...)>;
std::function<result_type()> func = std::bind(std::forward<Function>(f), std::forward<Args>(args)...);
auto task_ptr = std::make_shared<std::packaged_task<result_type()>>(func);
std::function<void()> wrapper_fuc = [task_ptr]() {
(*task_ptr)();
};
fuctions.push_back(wrapper_fuc);
return task_ptr->get_future();
}
int add(int a, int b) {
return a + b;
}
int main() {
futures.push_back(std::move(submit(add, 1, 2)));
futures.push_back(std::move(submit(add, 2, 2)));
futures.push_back(std::move(submit(add, 3, 2)));
futures.push_back(std::move(submit(add, 4, 2)));
futures.push_back(std::move(submit(add, 5, 2)));
futures.push_back(std::move(submit(add, 6, 2)));
futures.push_back(std::move(submit(add, 7, 2)));
futures.push_back(std::move(submit(add, 8, 2)));
std::cout << "do functions" << std::endl;
for (int i = 0; i < fuctions.size(); ++i) {
fuctions[i]();
}
std::cout << "functions done" << std::endl;
for (int i = 0; i < futures.size(); ++i) {
std::cout << "get result : " << futures[i].get() << std::endl;
}
}
this line fuctions[i]() raises the exception, detailed infomation is below
terminate called after throwing an instance of 'std::system_error'
what(): Unknown error -1
Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
I don't know why ....
