std::packaged_task<R(Args...)>::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 as if by INVOKE<R>(f, args...), where f is the stored task. 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.
Contents |
[edit]Parameters
| args | - | the parameters to pass on invocation of the stored task |
[edit]Return value
(none)
[edit]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.
[edit]Example
Run this code
#include <chrono>#include <functional>#include <future>#include <iostream>#include <memory>#include <thread>#include <utility> struct ProgramState {std::packaged_task<void()> task;std::future<void> future;std::thread worker;}; staticvoid worker(std::shared_ptr<ProgramState> state){ state->task.make_ready_at_thread_exit();// execute task right away auto status = state->future.wait_for(std::chrono::seconds(0));if(status ==std::future_status::timeout)std::cout<<"worker: future is not ready yet\n";elsestd::cout<<"worker: future is ready\n"; std::cout<<"worker: exit\n";} staticstd::shared_ptr<ProgramState> create_state(){auto state =std::make_shared<ProgramState>(); state->task =std::packaged_task<void()>{[]{std::cout<<"task: executed\n";}}; state->future = state->task.get_future(); state->worker =std::thread{worker, state};return state;} int main(){auto state = create_state(); state->worker.join();std::cout<<"main: worker finished\n"; auto status = state->future.wait_for(std::chrono::seconds(0));if(status ==std::future_status::timeout)std::cout<<"main: future is not ready yet\n";elsestd::cout<<"main: future is ready\n";}
Output:
task: executed worker: future is not ready yet worker: exit main: worker finished main: future is ready
[edit]See also
| executes the function (public member function) |
