1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // UNSUPPORTED: libcpp-has-no-threads 11 // UNSUPPORTED: c++98, c++03 12 13 // <future> 14 15 // class shared_future<R> 16 17 // template <class Clock, class Duration> 18 // future_status 19 // wait_until(const chrono::time_point<Clock, Duration>& abs_time) const; 20 21 #include <future> 22 #include <atomic> 23 #include <cassert> 24 25 enum class WorkerThreadState { Uninitialized, AllowedToRun, Exiting }; 26 typedef std::chrono::milliseconds ms; 27 28 std::atomic<WorkerThreadState> thread_state(WorkerThreadState::Uninitialized); 29 set_worker_thread_state(WorkerThreadState state)30 void set_worker_thread_state(WorkerThreadState state) 31 { 32 thread_state.store(state, std::memory_order_relaxed); 33 } 34 wait_for_worker_thread_state(WorkerThreadState state)35 void wait_for_worker_thread_state(WorkerThreadState state) 36 { 37 while (thread_state.load(std::memory_order_relaxed) != state); 38 } 39 func1(std::promise<int> p)40 void func1(std::promise<int> p) 41 { 42 wait_for_worker_thread_state(WorkerThreadState::AllowedToRun); 43 p.set_value(3); 44 set_worker_thread_state(WorkerThreadState::Exiting); 45 } 46 47 int j = 0; 48 func3(std::promise<int &> p)49 void func3(std::promise<int&> p) 50 { 51 wait_for_worker_thread_state(WorkerThreadState::AllowedToRun); 52 j = 5; 53 p.set_value(j); 54 set_worker_thread_state(WorkerThreadState::Exiting); 55 } 56 func5(std::promise<void> p)57 void func5(std::promise<void> p) 58 { 59 wait_for_worker_thread_state(WorkerThreadState::AllowedToRun); 60 p.set_value(); 61 set_worker_thread_state(WorkerThreadState::Exiting); 62 } 63 main()64 int main() 65 { 66 typedef std::chrono::high_resolution_clock Clock; 67 { 68 typedef int T; 69 std::promise<T> p; 70 std::shared_future<T> f = p.get_future(); 71 std::thread(func1, std::move(p)).detach(); 72 assert(f.valid()); 73 assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout); 74 assert(f.valid()); 75 76 // allow the worker thread to produce the result and wait until the worker is done 77 set_worker_thread_state(WorkerThreadState::AllowedToRun); 78 wait_for_worker_thread_state(WorkerThreadState::Exiting); 79 80 assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready); 81 assert(f.valid()); 82 Clock::time_point t0 = Clock::now(); 83 f.wait(); 84 Clock::time_point t1 = Clock::now(); 85 assert(f.valid()); 86 assert(t1-t0 < ms(5)); 87 } 88 { 89 typedef int& T; 90 std::promise<T> p; 91 std::shared_future<T> f = p.get_future(); 92 std::thread(func3, std::move(p)).detach(); 93 assert(f.valid()); 94 assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout); 95 assert(f.valid()); 96 97 // allow the worker thread to produce the result and wait until the worker is done 98 set_worker_thread_state(WorkerThreadState::AllowedToRun); 99 wait_for_worker_thread_state(WorkerThreadState::Exiting); 100 101 assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready); 102 assert(f.valid()); 103 Clock::time_point t0 = Clock::now(); 104 f.wait(); 105 Clock::time_point t1 = Clock::now(); 106 assert(f.valid()); 107 assert(t1-t0 < ms(5)); 108 } 109 { 110 typedef void T; 111 std::promise<T> p; 112 std::shared_future<T> f = p.get_future(); 113 std::thread(func5, std::move(p)).detach(); 114 assert(f.valid()); 115 assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout); 116 assert(f.valid()); 117 118 // allow the worker thread to produce the result and wait until the worker is done 119 set_worker_thread_state(WorkerThreadState::AllowedToRun); 120 wait_for_worker_thread_state(WorkerThreadState::Exiting); 121 122 assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready); 123 assert(f.valid()); 124 Clock::time_point t0 = Clock::now(); 125 f.wait(); 126 Clock::time_point t1 = Clock::now(); 127 assert(f.valid()); 128 assert(t1-t0 < ms(5)); 129 } 130 } 131