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++03, c++98, c++11, c++14 12 13 // FLAKY_TEST. 14 15 // <shared_mutex> 16 17 // class shared_mutex; 18 19 // void lock_shared(); 20 21 #include <shared_mutex> 22 #include <thread> 23 #include <vector> 24 #include <cstdlib> 25 #include <cassert> 26 27 #include "test_macros.h" 28 29 std::shared_mutex m; 30 31 typedef std::chrono::system_clock Clock; 32 typedef Clock::time_point time_point; 33 typedef Clock::duration duration; 34 typedef std::chrono::milliseconds ms; 35 typedef std::chrono::nanoseconds ns; 36 37 ms WaitTime = ms(250); 38 39 // Thread sanitizer causes more overhead and will sometimes cause this test 40 // to fail. To prevent this we give Thread sanitizer more time to complete the 41 // test. 42 #if !defined(TEST_HAS_SANITIZERS) 43 ms Tolerance = ms(50); 44 #else 45 ms Tolerance = ms(50 * 5); 46 #endif 47 48 void f() 49 { 50 time_point t0 = Clock::now(); 51 m.lock_shared(); 52 time_point t1 = Clock::now(); 53 m.unlock_shared(); 54 ns d = t1 - t0 - WaitTime; 55 assert(d < Tolerance); // within tolerance 56 } 57 58 void g() 59 { 60 time_point t0 = Clock::now(); 61 m.lock_shared(); 62 time_point t1 = Clock::now(); 63 m.unlock_shared(); 64 ns d = t1 - t0; 65 assert(d < Tolerance); // within tolerance 66 } 67 68 69 int main() 70 { 71 m.lock(); 72 std::vector<std::thread> v; 73 for (int i = 0; i < 5; ++i) 74 v.push_back(std::thread(f)); 75 std::this_thread::sleep_for(WaitTime); 76 m.unlock(); 77 for (auto& t : v) 78 t.join(); 79 m.lock_shared(); 80 for (auto& t : v) 81 t = std::thread(g); 82 std::thread q(f); 83 std::this_thread::sleep_for(WaitTime); 84 m.unlock_shared(); 85 for (auto& t : v) 86 t.join(); 87 q.join(); 88 } 89
