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      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 // void wait() const;
     18 
     19 #include <future>
     20 #include <cassert>
     21 
     22 void func1(std::promise<int> p)
     23 {
     24     std::this_thread::sleep_for(std::chrono::milliseconds(500));
     25     p.set_value(3);
     26 }
     27 
     28 int j = 0;
     29 
     30 void func3(std::promise<int&> p)
     31 {
     32     std::this_thread::sleep_for(std::chrono::milliseconds(500));
     33     j = 5;
     34     p.set_value(j);
     35 }
     36 
     37 void func5(std::promise<void> p)
     38 {
     39     std::this_thread::sleep_for(std::chrono::milliseconds(500));
     40     p.set_value();
     41 }
     42 
     43 int main()
     44 {
     45     typedef std::chrono::high_resolution_clock Clock;
     46     typedef std::chrono::duration<double, std::milli> ms;
     47     {
     48         typedef int T;
     49         std::promise<T> p;
     50         std::shared_future<T> f = p.get_future();
     51         std::thread(func1, std::move(p)).detach();
     52         assert(f.valid());
     53         f.wait();
     54         assert(f.valid());
     55         Clock::time_point t0 = Clock::now();
     56         f.wait();
     57         Clock::time_point t1 = Clock::now();
     58         assert(f.valid());
     59         assert(t1-t0 < ms(5));
     60     }
     61     {
     62         typedef int& T;
     63         std::promise<T> p;
     64         std::shared_future<T> f = p.get_future();
     65         std::thread(func3, std::move(p)).detach();
     66         assert(f.valid());
     67         f.wait();
     68         assert(f.valid());
     69         Clock::time_point t0 = Clock::now();
     70         f.wait();
     71         Clock::time_point t1 = Clock::now();
     72         assert(f.valid());
     73         assert(t1-t0 < ms(5));
     74     }
     75     {
     76         typedef void T;
     77         std::promise<T> p;
     78         std::shared_future<T> f = p.get_future();
     79         std::thread(func5, std::move(p)).detach();
     80         assert(f.valid());
     81         f.wait();
     82         assert(f.valid());
     83         Clock::time_point t0 = Clock::now();
     84         f.wait();
     85         Clock::time_point t1 = Clock::now();
     86         assert(f.valid());
     87         assert(t1-t0 < ms(5));
     88     }
     89 }
     90