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 // <mutex> 11 12 // template <class Mutex> class lock_guard; 13 14 // lock_guard(mutex_type& m, adopt_lock_t); 15 16 #include <mutex> 17 #include <thread> 18 #include <cstdlib> 19 #include <cassert> 20 21 std::mutex m; 22 23 typedef std::chrono::system_clock Clock; 24 typedef Clock::time_point time_point; 25 typedef Clock::duration duration; 26 typedef std::chrono::milliseconds ms; 27 typedef std::chrono::nanoseconds ns; 28 29 void f() 30 { 31 time_point t0 = Clock::now(); 32 time_point t1; 33 { 34 m.lock(); 35 std::lock_guard<std::mutex> lg(m, std::adopt_lock); 36 t1 = Clock::now(); 37 } 38 ns d = t1 - t0 - ms(250); 39 assert(d < ms(50)); // within 50ms 40 } 41 42 int main() 43 { 44 m.lock(); 45 std::thread t(f); 46 std::this_thread::sleep_for(ms(250)); 47 m.unlock(); 48 t.join(); 49 } 50
