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// explicit lock_guard(mutex_type& m); 15 16#include <mutex> 17#include <thread> 18#include <cstdlib> 19#include <cassert> 20 21std::mutex m; 22 23typedef std::chrono::system_clock Clock; 24typedef Clock::time_point time_point; 25typedef Clock::duration duration; 26typedef std::chrono::milliseconds ms; 27typedef std::chrono::nanoseconds ns; 28 29void f() 30{ 31 time_point t0 = Clock::now(); 32 time_point t1; 33 { 34 std::lock_guard<std::mutex> lg = m; 35 t1 = Clock::now(); 36 } 37 ns d = t1 - t0 - ms(250); 38 assert(d < ns(2500000)); // within 2.5ms 39} 40 41int main() 42{ 43 m.lock(); 44 std::thread t(f); 45 std::this_thread::sleep_for(ms(250)); 46 m.unlock(); 47 t.join(); 48} 49