mutex_try_to_lock.pass.cpp (1541B)
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 12 // <mutex> 13 14 // template <class Mutex> class unique_lock; 15 16 // unique_lock(mutex_type& m, try_to_lock_t); 17 18 #include <mutex> 19 #include <thread> 20 #include <cstdlib> 21 #include <cassert> 22 23 std::mutex m; 24 25 typedef std::chrono::system_clock Clock; 26 typedef Clock::time_point time_point; 27 typedef Clock::duration duration; 28 typedef std::chrono::milliseconds ms; 29 typedef std::chrono::nanoseconds ns; 30 31 void f() 32 { 33 time_point t0 = Clock::now(); 34 { 35 std::unique_lock<std::mutex> lk(m, std::try_to_lock); 36 assert(lk.owns_lock() == false); 37 } 38 { 39 std::unique_lock<std::mutex> lk(m, std::try_to_lock); 40 assert(lk.owns_lock() == false); 41 } 42 { 43 std::unique_lock<std::mutex> lk(m, std::try_to_lock); 44 assert(lk.owns_lock() == false); 45 } 46 while (true) 47 { 48 std::unique_lock<std::mutex> lk(m, std::try_to_lock); 49 if (lk.owns_lock()) 50 break; 51 } 52 time_point t1 = Clock::now(); 53 ns d = t1 - t0 - ms(250); 54 assert(d < ms(200)); // within 200ms 55 } 56 57 int main() 58 { 59 m.lock(); 60 std::thread t(f); 61 std::this_thread::sleep_for(ms(250)); 62 m.unlock(); 63 t.join(); 64 }