Defined in header <execution> | ||
template<class Sch> concept scheduler= | (1) | (since C++26) |
Helper tag type | ||
struct scheduler_t{}; | (2) | (since C++26) |
The conceptscheduler is modeled by types that areschedulers, that is, lightweight handlers to execution resources such as thread pools that work with the C++ execution library.
Given a scheduler of typeSch and execution environment of typeEnv such thatsender_in<schedule_result_t<Sch>, Env> is satisfied, then/*sender-in-of*/<schedule_result_t<Sch>, Env> is modeled.
The scheduler's copy constructor, destructor, equality comparison, or swap member functions must be non-throwing.
All of those member functions as well as the scheduler type'sschedule function must be thread-safe.
Two schedulers are equal only if they represent the same execution resource.
For a given schedulersch, the expressionget_completion_scheduler<set_value_t>(get_env(schedule(sch))) compares equal tosch.
For a given schedulersch, if the expressionget_domain(sch) is well-formed, then the expressionget_domain(get_env(schedule(sch))) is also well-formed and has the same type.
The destructor of a scheduler must not block pending completion of any receivers connected to the sender objects returned from schedule (the underlying resource may provide a separate API to wait for completion of submitted function objects)
simple wrapper forstd::execution::run_loop that constantly polls run_loop's queue on a single dedicated thread. Demo using draft reference implementation:https://godbolt.org/z/146fY4Y91
#include <execution>#include <iostream>#include <thread> class single_thread_context{ std::execution::run_loop loop_{};std::jthread thread_; public: single_thread_context(): thread_([this]{ loop_.run();}){} single_thread_context(single_thread_context&&)= delete; ~single_thread_context(){ loop_.finish();} std::execution::schedulerauto get_scheduler()noexcept{return loop_.get_scheduler();}}; int main(){ single_thread_context ctx; std::execution::senderauto snd= std::execution::schedule(ctx.get_scheduler())| std::execution::then([]{std::cout<<"Hello world! Have an int.\n";return015;})| std::execution::then([](int arg){return arg+42;}); auto[i]= std::this_thread::sync_wait(snd).value(); std::cout<<"Back in the main thread, result is "<< i<<'\n';}
Output:
Hello world! Have an int.Back in the main thread, result is 55
(C++26) | prepares a task graph for execution on a given scheduler (customization point object)[edit] |
